Ultrasonic bonding process for bonding nonwoven webs containing cellulose ester fibers

ABSTRACT

Process for ultrasonically bonding nonwoven webs comprising: providing a nonwoven web comprised of base fibers in an amount from 0 to 85 wt % and binder fibers in an amount from 15 to 100 wt %, based on the total weight of the nonwoven web; and ultrasonically bonding the nonwoven web to itself or another nonwoven web, wherein the binder fibers comprise cellulose ester fibers.

BACKGROUND OF THE INVENTION

Fibers comprised of the naturally occurring polymer cellulose have properties that are very desirable and useful for many nonwoven textiles particularly those utilized in disposable applications. Cellulosic nonwoven webs can readily absorb and wick aqueous fluids which is necessary for personal hygiene products such as diapers. Cellulose fibers are preferred for cleaning most contaminants from skin or hard surfaces particularly in conjunction with a solvent. In addition to aqueous absorbency, cellulose fiber webs have a high capacity for non-polar liquids such as motor or vegetable oil which makes cellulosic wipes also desirable for industrial and restaurant wipes respectively. In recent decades the plant based (hence carbon neutral) life cycle of cellulose based fibers has become a preferred feature in comparison with the 100% fossil-fuel based fibers (polypropylene, polyester etc.) that are also commonly utilized for disposable fabrics. The biodegradable nature of cellulosic fiber is also a preferred feature over the nondegradable fossil fuel based nonwoven fibers when utilized for most disposable applications.

Cellulose acetate is a subset of cellulose esters polymers that is created by chemically reacting acetic anhydride with cellulose in an aqueous solution. Cellulose diacetate (CDA) can be dissolved at high solids levels in acetone and solution spun into continuous filaments. These filaments in turn can be crimped and cut to create staple fiber that can baled and subsequently formed by water slurry, air stream, or mechanical card into a nonwoven web. The nonwoven web can then be bonded by suitable means into a useful fabric. However, thermal bonding is not a method for bonding webs comprised of cellulose fibers as native state cellulose (e.g. wood pulp, cotton) and reconstituted cellulose (e.g. viscose rayon, Tencel® rayon) do not exhibit thermoplastic properties. Further, many cellulose ester fibers have a glass transition temperature Tg above typical temperatures applied to commercial thermal bonding rolls, which are kept low to avoid thermally degrading other fibers.

The process for thermal bonding is desirably conducted at high productions speed. In contrast to cellulose esters, the viscose rayon or Tencel® rayon fibers noted above are comprised entirely of unmodified cellulose molecules and, therefore, have no thermoplastic properties. This limits fabric bonding methods for rayon fibers to either fiber to fiber friction (hydroentangling), adhesive applications (e.g. EVA emulsion), thermoplastic powder binder addition such as polyethylene (PE) powder, or the use of polypropylene/PE and PET/PE bicomponent fibers. The same bonding method limitations apply to natural cellulosics such as cotton, wood pulp, flax, and hemp fibers. The above bonding methods are more complex in execution than thermal bonding methods so a cellulose fiber than can be thermally bonded at production speeds is highly sought in the nonwovens industry.

There remains a need to develop a process that has the capability to bond nonwoven webs containing cellulose ester fibers at low temperatures and high rates. There is also a need to subject nonwoven webs containing cellulosic fibers, including rayons, to such a bonding process.

SUMMARY OF THE INVENTION

There is now provided a process for bonding nonwoven webs comprising:

-   -   a. providing a first nonwoven web comprised of base fibers in an         amount from 0 to 85 wt % and binder fibers in an amount from 15         to 100 wt %, based on the total weight of the nonwoven web; and     -   b. ultrasonically bonding the nonwoven web to itself, wherein         the binder fibers comprise cellulose ester fibers.

In embodiments, the binder fibers comprise 80 wt % or more of cellulose acetate fibers or are 100 wt % cellulose acetate fibers. In an embodiment, the nonwoven web comprises from 15 to 100 wt % cellulose acetate fibers.

In embodiments, the base fibers comprise non-thermoplastic cellulose fibers. In an embodiment, the base fibers comprise 80 wt % or more of non-thermoplastic cellulose fibers.

In an embodiment, the ultrasonic bonding forms a seam having a breaking strength that is at least 40% of the breaking strength of a single-stitch seam.

In embodiments, a process is provided for bonding nonwoven webs comprising: providing a first nonwoven web comprised of first base fibers in an amount from 0 to 85 wt % and first binder fibers in an amount from 15 to 100 wt %, based on the total weight of the first nonwoven web; and ultrasonically bonding the first nonwoven web to itself or to a second nonwoven web comprised of second base fibers and second binder fibers, wherein the first binder fibers comprise cellulose ester fibers.

In embodiments, a process is provided for bonding nonwoven webs comprising: providing a first nonwoven web comprised of first base fibers in an amount from 0 to 85 wt % and first binder fibers in an amount from 15 to 100 wt %, based on the total weight of the first nonwoven web; and ultrasonically bonding the first nonwoven web to a second nonwoven web comprised of second base fibers and second binder fibers, wherein the first binder fibers comprise cellulose ester fibers.

In the first binder fibers comprise 80 wt % or more of cellulose acetate fibers or are 100 wt % cellulose acetate fibers. In an embodiment, the first nonwoven web comprises from 15 to 100 wt % cellulose acetate fibers.

In embodiments, the first base fibers comprise non-thermoplastic cellulose fibers. In an embodiment, the first base fibers comprise 80 wt % or more of non-thermoplastic cellulose fibers.

In embodiments, the second nonwoven web comprises second base fibers in an amount from 0 to 85 wt % and second binder fibers in an amount from 15 to 100 wt %, based on the total weight of the second nonwoven web. In embodiments, the second binder fibers comprise cellulose ester fibers.

In embodiments, the second binder fibers comprise 80 wt % or more of cellulose acetate fibers or are 100 wt % cellulose acetate fibers. In an embodiment, the second nonwoven web comprises from 15 to 100 wt % cellulose acetate fibers.

In embodiments, the second base fibers comprise non-thermoplastic cellulose fibers. In an embodiment, the second base fibers comprise 80 wt % or more of non-thermoplastic cellulose fibers.

In embodiments, the process further comprises forming a laminate of said first and second nonwoven webs. In an embodiment, the laminate is not formed using an adhesive and does not comprise an adhesive. In an embodiment, the laminate is formed by bonding said first and second nonwoven webs using only ultrasonic bonding. In an embodiment, the laminate is biodegradable and compostable.

In embodiments, the first nonwoven web and second nonwoven web have the same composition. In other embodiments, the first nonwoven web and second nonwoven web have different compositions.

In embodiments, the first nonwoven web is formed by carding and hydroentanglement processes. In an embodiment, the second nonwoven web is formed by carding and hydroentanglement processes.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment or in combination with any of the mentioned embodiments of the invention, there is provided a process for bonding nonwoven web material comprising: providing a nonwoven web comprised of base fibers in an amount from 0 to 85 wt % and binder fibers in an amount from 15 to 100 wt %, based on the total weight of the nonwoven web; and ultrasonically bonding the nonwoven web to itself or to a second nonwoven web comprised of base fibers and binder fibers, wherein the binder fibers (in the nonwoven web) comprise cellulose ester fibers.

In the first step of the process, there is provided a nonwoven web. Nonwoven webs or sheets are planar, flat, or tufted porous structures containing entangled fibers (filaments or staple) that do not have a uniform identifiable entanglement pattern such as would be seen with knitted or woven fabrics. Typically, there is no intentional entanglement pattern at the fiber to fiber level. In embodiments, the fibers being formed into a nonwoven are subjected to a carding process prior to entangling the fibers. In embodiments, the carding is a mechanical process that disentangles, cleans and intermixes the fibers to produce a continuous web or sliver suitable for subsequent processing. In embodiments, this is achieved by passing the fibers between differentially moving surfaces covered with card clothing under conditions to break up locks and unorganized clumps of fiber and to align the individual fibers to be generally parallel with each other. While carding operations orient the fibers in a direction, their ultimate entanglement disposition in the web is random. The entanglement of the fibers can be accomplished through spun bond or laced, dry laid, and melt blowing processes. The nonwoven webs are not woven, knitted, or weaved.

In embodiments, the carded web is subjected to hydroentanglement. In embodiments, the hydroentanglement is a bonding process for the fibrous web made by either carding or air laying, where the resulting bonded fabric is nonwoven. In embodiments, the web is processed on a conveyor belt and the hydroentanglement uses fine, high pressure jets of water which penetrate the web, hit the conveyor belt, and bounce back causing the fibers to entangle. In embodiments, the hydroentanglement results in a spunlaced nonwoven, where the nonwoven is entangled on conveyors with a patterned weave which provides the nonwoven with a lacy appearance. In embodiments, the water pressure can have a direct bearing on the strength of the web, and very high pressures can not only entangle but can also split fibers into micro- and nano-fibers which can give the resulting hydroentangled nonwoven a leather-like or even silky texture. In embodiments, this type of nonwoven can be as strong and tough as woven fabrics made from the same fibers.

The form of the webs are not limited; and can include webs or sheets that are flat or tufted, or bats. The nonwoven web can be a dry laid web and can be monolayered or multilayered.

The nonwoven web contains binder fibers and base fibers. The base fibers are any fibers that are not thermoplastic and do not fuse to each other or other fibers with application of heat and pressure without charring or thermally degrading the fiber. The binder fibers are thermoplastic fibers or have a thermoplastic component to them, and include at least cellulose ester fibers. The cellulose ester fibers are thermoplastic, and these fibers differ from native state cellulose fibers or reconstituted cellulose fibers in the key property of thermoplastic behavior. That is, the cellulose ester fibers have a glass transition temperature and, under the proper conditions, can be thermally fused to themselves or to other fibers such as rayon or polyester.

The cellulose ester fibers can be monocomponent fibers (e.g. the entire fiber is a cellulose ester) or a bicomponent fibers. Bi-component fibers include a continuous phase containing a disperse phase such as islands in the sea, or core-sheath configurations, or side by side configuration, or other configurations known in the art. The process of preparing and bonding a low melt temperature bicomponent binder fiber is described in detail in U.S. Pat. No. 3,589,956, incorporated herein by reference.

Desirably, at least a portion of the binder fibers are mono-component fibers, meaning that there are no discrete phases, such as islands, domains, or sheaths of alternate polymers in the fiber other than the CE polymer. For example, a mono-component fiber can be entirely made of CE polymer, or a melt blend of a CE polymer and a different polymer. Desirably, at least 60% of the composition of the CE fibers are CE polymers, or at least 70%, or at least 75%, or at least 80%, or at least 90%, or at least 92%, or at least 95%, or at least 98%, or at least 99%, and most preferably 100% by weight of the CE fibers are CE polymers, based on the weight of all polymers in the CE fiber having a number average molecular weight of over 500 (or alternatively based on the weight of all polymers used to spin filaments from which the CE fibers are made). For clarity, these percentages do not exclude spin or cutting finishes applied to the filaments once spun or other additives which have a number average molecular weight of less than 500.

Suitable quantities of mono-component fibers include at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. %, or at least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, or at least 98 wt. %, or 100 wt. % mono-component fibers based on the weight of all fibers containing a cellulose ester polymer.

The process of the invention does not rely upon binder powders, binder particles, or films to provide strength and toughness. Binding powders and particles typically consist of a polyolefin, low molecular weight polyamides, or copolymers of vinyl acetate and vinyl chloride, or other inexpensive thermoplastic powders and particles. Dispensing with binder powders, particles, or films reduces the cost of the fabric, and avoids the problem of matching powder particle size and size distribution with the particular web and avoids the problem of providing a uniform distribution of binder throughout the web.

Desirably, the nonwoven web contains, or is embedded, coated, layered, or laid up with binders or thermoplastic films, sheets, powders, or particles in an amount of not more than 30 wt. %, or not more than 20 wt. %, or not more than 10 wt. %, or not more than 5 wt. %, or not more than 3 wt. %, or not more than 1 wt. %, or not more than 0.5 wt. %, or not more than 0.1 wt. %, based on the weight of the nonwoven web or fabric, or does not contain, or is not embedded, coated, layered, or laid up with binders or thermoplastic films, sheets, powders, or particles.

Desirably, at least a portion of the binder fibers are cellulose ester fibers. In one embodiment or in combination with any of the mentioned embodiments, at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. %, or at least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, or at least 98 wt. %, or 100 wt. % of the binder fibers are cellulose ester fibers or mono-component cellulose ester fibers, based on the weight of all binder fibers in the non-woven web.

In one embodiment or in combination with any of the mentioned embodiments, the binder fibers include cellulose ester fibers, and the cellulose ester fibers are made from cellulose ester polymers. Suitable CE polymers include cellulose derivatized with a reactive compound to generate at least one ester linkage at the hydroxyl site on the cellulose backbone, such as cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, cellulose propionate butyrate, and mixtures thereof. Although described herein with reference to “cellulose acetate,” it should be understood that one or more of the above cellulose acid esters or mixed esters may also be used to form the fibers. Various types of cellulose esters are described, for example, in U.S. Pat. Nos. 1,698,049; 1,683,347; 1,880,808; 1,880,560; 1,984,147, 2,129,052; and 3,617,201, each of which is incorporated herein by reference to the extent not inconsistent with the present disclosure. As used herein, regenerated or reconstituted cellulose (e.g., viscose, rayon, or lyocell) and the fibers made therefrom are not classified as CE polymers or cellulose ester fibers or binder fibers.

Cellulose esters can be characterized as a modified cellulose polymer in that the cellulose backbone remains intact after the chemical substitution of acyl (e.g. acetyl) groups for a portion of the hydroxyl groups on the cellulose polymer chain. Cellulose esters retain many functional features of native state cellulose such as water absorbency, oil absorbency, biodegradability, and a visual appearance and tactile feel similar to that of textile grade cellulosic fibers such as Tencel® and bleached cotton.

The cellulose ester can have a degree of substitution that is not limited, although a degree of substitution in the range of from 1.8 to 2.9 is desirable. As used herein, the term “degree of substitution” or “DS” refers to the average number of acyl substituents per anhydroglucose ring of the cellulose polymer, wherein the maximum degree of substitution is 3.0. In some cases, the cellulose ester used to form fibers as described herein may have a degree of substitution of at least 1.2, or at least 1.5, or at least 1.8, or at least 1.90, or at least 1.95, or at least 2.0, or at least 2.05, or at least 2.1, or at least 2.15, or at least 2.2, or at least 2.25, or at least 2.3 and/or not more than about 2.9, or not more than 2.85, or not more than 2.8, or not more than 2.75, or not more than 2.7, or not more than 2.65, or not more than 2.6, or not more than 2.55, or not more than 2.5, or not more than 2.45, or not more than 2.4, or not more than 2.35. Desirably, at least 90, or at least 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99 percent of the cellulose ester fibers have a degree of substitution of at least 2.15, or at least 2.2, or at least 2.25.

Typically, acetyl groups can make up at least about 30, or at least about 40, or at least about 50, or at least about 60, or at least about 70, or at least about 80, or at least about 90, or at least about 95, or at least about 98, or 100% of the total acyl substituents (which do not include the hydroxyl groups). Desirably, greater than 90 weight percent, or greater than 95%, or greater than 98%, or greater than 99%, and up to 100 wt. % of the total acyl substituents are acetyl substituents (C2). The cellulose ester can have no acyl substituents having a carbon length of greater than 2.

In an embodiment or in any of the mentioned embodiments, the DS of the cellulose ester polymer is not more than 2.5, or not more than 2.45. Both the industrial and home compostability of CE fibers is most effective when made with cellulose esters having a DS of not more than 2.5. Additionally, those CE fibers made with cellulose ester polymers having a DS of not more than 2.5 are also soil biodegradable under the ISO 17566 test method.

The cellulose ester may have a weight-average molecular weight (Mw) of not more than 90,000, measured using gel permeation chromatography with N-methyl-2-pyrrolidone (NMP) as the solvent. In some case, the cellulose ester may have a molecular weight of at least about 10,000, at least about 20,000, 25,000, 30,000, 35,000, 40,000, or 45,000 and/or not more than about 100,000, 95,000, 90,000, 85,000, 80,000, 75,000, 70,000, 65,000, 60,000, or 50,000.

The cellulose ester may be formed by any suitable method, and desirably the CE fibers are obtained from filaments formed by the solvent spun method, which is a method distinct from a precipitation method or emulsion flashing. In a solvent spun method, the cellulose ester flake is dissolved in a solvent, such as acetone or methyl ethyl ketone, to form a “solvent dope,” which can be filtered and sent through a spinnerette to form continuous cellulose ester filaments. In some cases, up to about 3 wt. % or up to 2 wt %, or up to 1 weight percent, or up to 0.5 wt. %, or up to 0.25 wt. %, or up to 0.1 wt. % based on the weight of the dope, of titanium dioxide or other delusterant may be added to the dope prior to filtration, depending on the desired properties and ultimate end use of the fibers, or alternatively, no titanium dioxide is added. The continuous cellulose ester filaments are then cut to the desired length if a staple fiber is desired, leading to CE fibers having low cut length variability, and consistent L/D ratios, and the ability to supply them as dry fibers. By contrast, cellulose ester forms made by the precipitation method have low length consistency, have a random shape, a wide DPF distribution, have a wide L/D distribution, cannot be crimped, and are supplied wet.

In some cases, the solvent dope or flake used to form the CE fibers may include some or no additives in addition to the cellulose ester. Such additives can include, but are not limited to, plasticizers, antioxidants, thermal stabilizers, pro-oxidants, acid scavengers, inorganics, pigments, and colorants.

At the spinnerette, the solvent dope can be extruded through a plurality of holes to form continuous cellulose ester filaments. At the spinnerette, filaments may be drawn to form bundles of several hundred, or even thousand, individual filaments. Each of these bundles may include at least 100, or at least 150, or at least 200, or at least 250, or at least 300, or at least 350, or at least 400 and/or not more than 1000, or not more than 900, or not more than 850, or not more than 800, or not more than 750, or not more than 700 fibers. The spinnerette may be operated at any speed suitable to produce filaments, which are then assembled into bundles having desired size and shape.

One or more types of finishes may be applied to the fibers. The method of application is not limited and can include the use of spraying, wick application, dipping, or use of squeeze, lick, or kiss rollers. The location for applying a finish to a fiber can vary depending on the function of the finish. For example, the lubricant finish can be applied after spinning and before crimping, or before gathering the fibers into a bundle. Cutting lubricants and/or antistatic lubricants can be applied before or after crimping and prior to drying. Suitable amounts of all finishes (whether lubricant, cutting lubricant, antistatic electricity finish, or otherwise) on the CE fibers can be at least about 0.01, or at least 0.02, or at least 0.05, or at least 0.10, or at least 0.15, or at least 0.20, or at least 0.25, or at least 0.30, or at least 0.35, or at least 0.40, or at least 0.45, or at least 0.50, or at least 0.55, or at least 0.60 percent finish-on-yarn (FOY) relative to the weight of the dried CE staple fiber. Alternatively, or in addition, the cumulative amount of finish may be present in an amount of not more than about 2.5, or not more than 2.0, or not more than 1.5, or not more than 1.2, or not more than 1.0, or not more than 0.9, or not more than 0.8, or not more than 0.7 percent finish-on-yarn (FOY) based on the total weight of the dried fiber. The amount of finish on the fibers as expressed by weight percent may be determined by solvent extraction. As used herein “FOY” or “finish on yarn” refers to the amount of finish on the tow band less any added water, and in the context of the nonwoven webs and fabrics, the percentage on yarn or tow would be deemed to correspond to the percentage of finish on the CE fibers present in the nonwoven webs and fabrics. If a finish is applied, the desired cumulative amount of finish on the fibers is from 0.10 to 2.0, or 0.10 to 1.90, or 0.10 to 1.80, or 0.20 to 1.70, or 0.20 to 1.5, or 0.20 to 1.3, or 0.20 to 1.1, or 0.30 to 1.0, or 0.30 to 2, or 0.30 to 1.90, or 0.30 to 1.70, or 0.30 to 1.5, or 0.3 to 1.2, or 0.3 to 1, each as % FOY.

The CE fibers used to make the nonwoven web, or as added to any apparatus to make the nonwoven web, can include some plasticizer or no plasticizer. In one embodiment or in combination with any of the mentioned embodiments, the CE fibers, contain not more than, or have added to the filaments used to make the CE fibers, not more than 20, or not more than 15, or not more than 12, or not more than 10, or not more than 9, or not more than 8, or not more than 7, or not more than 6, or not more than 5.5, or not more than 5, or not more than 4, or not more than 3, or not more than 2, or not more than 1.5, or not more than 1, or not more than 0.5, or not more than 0.25, or not more than 0.10, or nor more than 0.05, or not more than 0.01, or not more than 0.007, or not more than 0.005, or not more than 0.003, or not more than 0.001, or not more than 0.0007, in each case wt. % plasticizer based either as FOY, or based on the weight of the CE fibers; or the CE fibers contain no added plasticizer, whether virgin CE fibers, or waste/recycle CE fibers, or both. When present in a CE staple fiber before making the nonwoven web, the plasticizer may be incorporated into the fiber itself by spinning a dope containing a plasticizer, or contained in a flake used to make the dope, or the plasticizer may be applied to the surface of the fiber or filament by any of the methods used to apply a finish. If desired, the plasticizer can be contained in the finish formulation.

In one embodiment or in combination with any of the mentioned embodiments, no plasticizers are added to the CE fibers (whether virgin or post-consumer fibers or recycle fibers) used to make the nonwoven web. In this context, while recycle fibers can contain plasticizer when made in their virgin form, they are deemed not to have a plasticizer “added” if no plasticizer is applied to the post-consumer or recycle fibers. In another embodiment, the CE fibers used to make the nonwoven web do not contain a plasticizer.

Plasticizers are compounds that can decrease the glass transition temperature of a polymer. Examples of plasticizers suitable for addition to the CE fibers or to the nonwoven web, include, but are not limited to, aromatic polycarboxylic acid esters, aliphatic polycarboxylic acid esters, lower fatty acid esters of polyhydric alcohols, and phosphoric acid esters. Further examples can include, but are not limited to, the phthalate acid acetates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, dimethoxyethyl phthalate, ethyl phthalylethyl glycolate, butyl phthalylbutyl glycolate, levulinic acid esters, dibutyrates of triethylene glycol, tetraethylene glycol, pentaethylene glycol, tetraoctyl pyromellitate, trioctyl trimellitate, dibutyl adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, diethyl azelate, dibutyl azelate, dioctyl azelate, glycerol, trimethylolpropane, pentaerythritol, sorbitol, glycerin, glycerin (or glyceryl) triacetate (triacetin), diglycerin tetracetate, triethyl phosphate, tributyl sebacate, triethyl phosphate, tributyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, and tricresyl phosphate, triethyl citrate, polyethylene glycol, polyethylene adipate, polyethylene succinate, polypropylene glycol, polyglycolic acid, polybutylene adipate, polycaprolactone, polypropiolactone, valerolactone, polyvinylpyrrolidone, and other plasticizers having a weight average molecular weight of 200 to 800, dimethyl sebacate, glycerol, monostearate, sorbitol, erythritol, glucidol, mannitol, sucrose, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol caprate caprylate, butylene glycol, pentamethylene glycol, hexamethylene glycol, diisobutyl adipate, oleic amide, erucic amide, palmitic amide, dimethyl acetamide, dimethyl sulfoxide, methyl pyrrolidone, tetramethylene sulfone, oxamonoacids, oxa diacids, polyoxa diacids, diglycolic acids, acetyl triethyl citrate, tri-n-butyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n-hexyl citrate, alkyl lactates, phthalate polyesters, adipate polyesters, glutate polyesters, diisononyl phthalate, diisodecyl phthalate, dihexyl phthalate, alkyl alylether diester adipate, dibutoxy ethoxyethyl adipate, and mixtures thereof.

The CE fibers (whether virgin or recycle/post-consumer) used to make the nonwoven web, or in the nonwoven web, can include at least about 90, or at least 90.5, or at least 91, or at least 91.5, or at least 92, or at least 92.5, or at least 93, or at least 93.5, or at least 94, or at least 94.5, or at least 95, or at least 95.5, or at least 96, or at least 96.5, or at least 97, or at least 97.5, or at least 98, or at least 98.5, or at least 99, or at least 99.5, or at least 99.9, or at least 99.99, or at least 99.995, or at least 99.999 percent cellulose ester, based on the total weight of the fiber. In embodiments, the CE fibers used to make the nonwoven web, or in the nonwoven web, may include or contain not more than 15, or not more than 10, or not more than 9.5, or not more than 9, or not more than 8.5, or not more than 8, or not more than 7.5, or not more than 7, or not more than 6.5, or not more than 6, or not more than 5.5, or not more than 5, or not more than 4.5, or not more than 4, or not more than 3.5, or not more than 3, or not more than 2.5, or not more than 2, or not more than 1.5, or not more than 1, or not more than 0.5, or not more than 0.1, or not more than 0.01, or not more than 0.005, or not more than 0.001, or not more than 0.0005, or not more than 0.0001 weight percent of plasticizers, or optionally all additives, in the cellulose ester polymer or deposited onto the cellulose ester fiber or contained on or in the CE staple fiber, including but not limited to the specific additives listed herein.

In one embodiment or in combination with any of the mentioned embodiments, the CE fibers used to make the nonwoven web, prior to their combination with base fibers or prior to carding, already contain a plasticizer. The plasticizer can be added in the solvent dope or contained in the flake used to make the dope. The plasticizer can be added onto the (i) filament fiber, (i) the bundle, or (iii) the tow band, in each case prior to baling the fibers, or prior to drying the fibers, or prior to cutting the fibers, or prior to crimping the fibers. The method of addition is not limited and can as described above. The amount of plasticizer on the fiber can be as described above.

Turning to the manufacture of the CE fibers, multiple bundles may be assembled into a filament band such as, for example, a crimped or uncrimped tow band. The filament band may be of any suitable size and, in some embodiments, may have a total denier of at least about 10,000, or at least 15,000, or at least 20,000, or at least 25,000, or at least 30,000, or at least 35,000, or at least 40,000, or at least 45,000, or at least 50,000, or at least 75,000, or at least 100,000, or at least 150,000, or at least 200,000, or at least 250,000, or at least 300,000. Alternatively, or in addition, the total denier of the tow band is not more than about 5,000,000, or not more than 4,500,000, or not more than 4,000,000, or not more than 3,500,00, or not more than 3,000,000, or not more than 2,500,000, or not more than 2,000,000, or not more than 1,500,000, or not more than 1,000,000, or not more than 900,000, or not more than 800,000, or not more than 700,000, or not more than 600,00, or not more than 500,000, or not more than 400,000, or not more than 350,000, or not more than 300,000, or not more than 250,000, or not more than 200,000, or not more than 150,000, or not more than 100,000, or not more than 95,000, or not more than 90,000, or not more than 85,000, or not more than 80,000, or not more than 75,000, or not more than 70,000.

The linear denier per filament (weight in g of 9000 m fiber length), or DPF, of the CE filaments and of the corresponding CE fibers (whether CE staple fibers or CE continuous fibers), are desirably within a range of 0.5 to less than 20. The particular method for measurement is not limited, and include ASTM 1577-07 using the FAVIMAT vibroscope procedure if filaments can be obtained from which the staple fibers are cut, or a width analysis using any convenient optical microscopy or Metso.

The DPF can also be correlated to the maximum width of a fiber. The maximum width of a fiber is measured as the longest outermost diameter dimension, and in the case of any fiber than is not round, a convenient method for measuring the longest outer diameter is to spin the fiber. Table 1 illustrates a sample of convenient correlation of DPF to maximum widths (or outer diameter) of the fibers, regardless of shape and including multi-lobal shapes.

TABLE 1 DPF Approximate width (microns) 1.6 22 2.0 25 2.4 28 2.8 30 3.2 32 3.6 34 4.0 36

Desirably, the DPF of the filaments, and of the CE fibers, are within a range of 0.5 to 17, or 1.2 to 15, or 0.5 to 10, or 1.2 to 10, 0.5 to 8, or 0.5 to less than 5, or 1 to 4, or 1 to 3, or 1.0 to 2.8, or 1.0 to 2.5, or 1.0 to 2.2, or 1.0 to 2.1, or more desirably from 1.2 to less than 3, or 1.2 to 2.8, or 1.2 to 2.5, or 1.2 to 2.3, or 1.2 to 2, or 1.2 to less than 2.0, or 1.2 to 1.9, or 1.1 to 1.9, or 1.1 to 1.8.

In another embodiment or in any one of the mentioned embodiments, the maximum width of the fibers are less than 100 microns, or not more than 80 microns, or not more than 60 microns, or not more than 50 microns, or not more than 40 microns, or not more than 36 microns, or not more than 31 microns, or not more than 30 microns, or not more than 28 microns, or not more than 27 microns, or not more than 26 microns, or not more than 25 microns, or not more than 24.5 microns, or not more than 24 microns.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a DPF within +/−20% of any one of the above stated DPF. Alternatively, at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a DPF within +/−15% of any one of the above stated DPF; or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a DPF within +/−10% of any one of the above stated DPF. Desirably, at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a DPF within +/−15%, or within +/−10% of any one of the above stated DPF.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, the DPF can have a small distribution span satisfying the following formula:

${\frac{{d90} - {d10}}{d50}*100} \leq S$

where d is based on the median DPF, d₉₀ is the value at which 90% of the fibers have a DPF less than target DPF, d₁₀ is the value at which 10% of the fibers have a DPF less than the target DPF, d₅₀ is the value at which 50% of the fibers have a DPF less than the target DPF and 50% of fibers have a DPF more than the target DPF, and S is 40%, or 35%, or 30%, or 25%, or 20%, or 15%, or 13%, or 10%, or 8%, or 7%.

The individual cellulose ester filaments discharged from the spinnerette, and the CE fibers, may have any suitable transverse cross-sectional shape. Exemplary cross-sectional shapes include, but are not limited to, round or other than round (non-round). Non-round shapes include Y-shaped or other multi-lobal shapes such as I-shaped (dog bone), closed C-shaped, X-shaped, or crenulated shapes. When a cellulose ester filament, or CE staple fiber, has a multi-lobal cross-sectional shape, it may have at least 3, or 4, or 5, or 6 or more lobes. In some cases, the filaments may be symmetric along one or more, two or more, three or more, or four or more axes, and, in other embodiments, the filaments may be asymmetrical. As used herein, the term “cross-section” generally refers to the transverse cross-section of the filament measured in a direction perpendicular to the direction of elongation of the filament. The cross-section of the filament may be determined and measured using Quantitative Image Analysis (QIA). Staple fibers will have a cross-section similar to the filaments from which they are formed without mechanically deforming the staple fibers.

In some embodiments, the cross-sectional shape of an individual cellulose ester filament and the CE fibers may be characterized according to its deviation from a round cross-sectional shape. In some cases, this deviation from perfectly round can be characterized by the shape factor of the filament, which is determined by the following formula: Shape Factor=Average Cross Sectional Perimeter/(4π×Average Cross-Sectional Area)½. The shape factor of filament or CE fibers having a perfect round cross-sectional shape is 1. In some embodiments, the shape factor of the individual cellulose ester filaments or CE fibers is at least 1.5 or at least 1.7, or at least 2, or at least 2.5, or at least 2.7, or at least 3, or at least 3.2, or at least 3.5, or at least 4. Fibers in this category are typically tri-lobal or Y shaped. In another embodiment, the shape factor of the individual cellulose ester filamants or CE staple fibers are not more than 1.5, or not more than 1.45, or not more than 1.40, or not more than 1.35, or not more than 1.30, or not more than 1.25, or not more than 1.20, or not more than 1.15, or not more than 1.10. Fibers in this category are typically referred to as round which can include crenulated fibers. Fibers having a good round shape are those a shape factor of not more than 1.35, or not more than 1.3, particularly those having a shape factor of not more than 1.25. The shape factor can be calculated from the cross-sectional area of a filament, which can be measured using QIA.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97%, or at least 99% of the CE fibers have the stated shape.

After multiple bundles are assembled into a filament yarn (or tow band), it may be passed through a crimping zone wherein a patterned wavelike shape may be imparted to at least a portion, or substantially all, of the individual filaments. In some cases, the filaments may not be crimped, and the uncrimped filaments may be passed directly from the spinnerette to a drying zone. When used, the crimping zone includes at least one crimping device for mechanically crimping the filament yarn. Filament yarns desirably are not crimped by thermal or chemical means (e.g., hot water baths, steam, air jets, or chemical coatings), but instead are mechanically crimped using a suitable crimper. One example of a suitable type of mechanical crimper is a “stuffing box” or “stuffer box” crimper that utilizes a plurality of rollers to generate friction, which causes the fibers to buckle and form crimps. Other types of crimpers may also be suitable. Examples of equipment suitable for imparting crimp to a filament yarn are described in, for example, U.S. Pat. Nos. 9,179,709; 2,346,258; 3,353,239; 3,571,870; 3,813,740; 4,004,330; 4,095,318; 5,025,538; 7,152,288; and 7,585,442, each of which is incorporated herein by reference to the extent not inconsistent with the present disclosure. In some cases, the crimping step may be performed at a rate of at least about 50 m/min (or in each case at least 75, 100, 125, 150, 175, 200, 225, 250 m/min). Typically, the crimping rate is not more than about 750 m/min (or in each case not more than 475, 450, 425, 400, 375, 350, 325, or 300 m/min).

In one embodiment or in combination with any of the mentioned embodiments, the CE fibers are crimped CE staple fibers, and the crimped CE fibers have an average effective length that is not more than 85 percent of the actual length of the crimped CE fibers. The effective length refers to the maximum dimension between any two points of a fiber and the actual length refers the end-to-end length of a fiber if it were perfectly straightened. If a fiber is straight, its effective length is the same as its actual length. However, if a fiber is curved and/or crimped, its effective length will be less than its actual length, where the actual length is the end-to-end length of the fiber if it were perfectly straightened. In one embodiment or in combination with any of the mentioned embodiments or in any one of the embodiments described herein, the crimped fibers have an average effective length that is not more than 80, or not more than 75, or not more than 65, or not more than 50, or not more than 40, or not more than 30, or not more than 20 percent of the actual length of the bent fibers.

Low DPF CE fibers can be susceptible to breakage when cut from the filaments, or when further processed, compared to the normal frequency of crimps imparted to higher denier fibers typically used in cigarette filter tow. Crimping is a useful component of the CE fiber to enhance cohesion and entanglement with other fibers and with each other. However, if a low DPF fiber is used, a lower frequency of crimps is desirable to minimize fiber breakage when the filaments are cut to staple and when they are further processed or handled prior to their combination with the cellulosic fibers, and also to retain a high degree of retained tenacity. As used herein, the term “retained tenacity” refers to the ratio of the tenacity of a crimped filament (or staple fiber) to the tenacity of an identical but uncrimped filament (or staple fiber), expressed as a percent. For example, a crimped fiber having a tenacity of 1.3 gram-force/denier (g/denier) would have a retained tenacity of 87 percent if an identical but uncrimped fiber had a tenacity of 1.5 g/denier.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, the crimped CE filaments and staple fibers are capable of having a retained tenacity of at least about 40%, or at least 50%, or at least 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%_(.)

While the CE fibers contained in the nonwoven web and fabric may be crimped or uncrimped or obtained from filaments which were uncrimped or crimped, In one embodiment or in combination with any of the mentioned embodiments, the CE fibers (whether continuous or staple) contained in the nonwoven web or fabric have, or are obtained from continuous filaments which were crimped at, a crimp frequency of at least 5, or at least 7, or at least 10, or at least 12, or at least 13, or at least 15, or at least 17, and up to 30, or up to 27, or up to 25, or up to 23, or up to 20, or up to 19 crimps per inch (CPI), measured according to ASTM D3937-12. Higher than 30 CPI tends to result in excess breakage in the cutting of filaments to staple at the small cut lengths described below, and also reduces their retained tenacity. Fewer than 5 CPI will result in too few CE fibers manifesting a crimp when small cut lengths are employed. Desirably, the average CPI of the filaments used to make the CE fibers is a value from 6 to 30 CPI, or 7 to 30 CPI, or 7 to 27 CPI, or 7 to 25 CPI, or 7 to 23 CPI, or 8 to 20 CPI, or 8 to 30 CPI, or 9 to 27 CPI, or 8 to 25 CPI, or 8 to 23 CPI, or 9 to 20 CPI, or 7 to 18 CPI, or 7 to 16 CPI.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, the ratio of the crimp frequency CPI to DPF can be greater than about 2.75:1, or greater than 2.80:1, or greater than 2.85:1, or greater than 2.90:1, or greater than 2.95:1, or greater than 3.00:1, or greater than 3.05:1, or greater than 3.10:1, or greater than 3.15:1, or greater than 3.20:1, or greater than 3.25:1, or greater than 3.30:1, or greater than 3.35:1, or greater than 3.40:1, or greater than 3.45:1, or greater than 3.50:1. In some cases, this ratio may be even higher, such as, for example, greater than about 4:1, or greater than 5:1, or greater than 6:1, or greater than or greater than 7:1 particularly when, for example, the fibers being crimped are relatively fine.

The ratio of the CPI to the DPF is a useful measure to ensure that the proper CPI is imparted for a given DPF and retain the balance of necessary crimp frequency and tenacity for a given DPF, particularly when considering the use of CE staple fibers. Examples of desirable ratios of CPI:DPF include from 4:1 to 20:1, and especially 5:1 to 14:1, or 7:1 to 12:1.

When crimped, the crimp amplitude of the fibers may vary and can, for example, be at least about 0.85, or at least 0.90, or at least 0.93, or at least 0.96, or at least 0.98, or at least 1.00, or at least 1.04 mm. Additionally, or in the alternative, the crimp amplitude of the fibers can be up to 1.75, or up to 1.70, or up to 1.65, or up to 1.55, or up to 1.35, or up to 1.28, or up to 1.24, or up to 1.15, or up to 1.10, or up to 1.03, or up to 0.98 mm.

In an embodiment, the CE staple fibers may have a crimp ratio of at least about 1:1. As used herein, “crimp ratio” refers to the ratio of the non-crimped tow length to the crimped tow length. In some embodiments, the staple fibers may have a crimp ratio of at least about 1:1, at least about 1.1:1, at least about 1.125:1, at least about 1.15:1, or at least about 1.2:1.

Crimp amplitude and crimp ratio are measured according to the following calculations, with the dimensions referenced being shown in FIG. 2: Crimped length (Lc) is equal to the reciprocal of crimp frequency (1/crimp frequency), and the crimp ratio is equal to the straight length (L0) divided by the crimped length (L0:Lc). The amplitude (A) is calculated geometrically, as shown in FIG. 2, using half of the straight length (L0/2) and half of the crimped length (Lc/2). The uncrimped length is simply measured using conventional methods.

In one embodiment or in combination with any of the mentioned embodiments, the crimped CE fibers (whether continuous or staple, and especially staple) desirably can have one or more of the following features:

-   -   a) a crimp frequency of 7 to 30 CP, or 7 to 25 CPI, or 7 to 23         CPI, or 7 to 20 CPI, or 8 to 30 CPI, or 8 to 27 CPI, or 8 to 25         CPI, or 8 to 23 CPI, or 8 to 20 CPI crimps per inch, or     -   b) a crimp amplitude of at least 1.0 mm, or     -   c) an average effective length that is not more than 75% of the         actual length, or     -   d) a retained tenacity of at least 80%, or     -   e) a CPI:DPF of 5:1 to 14:1, or 7:1 to 12:1, or     -   f) any combination of two or more of the above.

After crimping (or, if not crimped, after spinning), the fibers may further be dried in a drying zone in order to reduce the moisture and/or solvent content of the filament yarn or tow band. In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, the CE fibers are dry, as further explained below.

The CE staple fiber can have a moisture content of not more than 30 wt. % moisture, or not more than 25 wt. % moisture, or not more than 23 wt. % moisture, or not more than 20 wt. % moisture, or not more than 18 wt. % moisture, or not more than 15 wt. % moisture, or not more than 13 wt. % moisture, or not more than 10 wt. % moisture, or not more than 9 wt. % moisture, or not more than 8 wt. % moisture, as determined by oven dryness, prior to forming the nonwoven web. In one embodiment or in combination with any of the mentioned embodiments, the moisture content on the CE fibers is in substantial equilibrium with the environment in which the CE fibers are stored for at least 8 hours prior to carding or forming the nonwoven web. The final moisture content, or level of dryness, of the filament yarn (or tow band), and of the CE fibers, particularly between cutting and combining with base fibers, or on the fibers added to form the nonwoven web (or on the nonwoven web) prior to the formation of the nonwoven web, can be at least 1 wt. %, and desirably is at least about 1 wt. %, or at least 2 wt. %, or at least 3 wt. %, or at least 3.5 wt. %, or at least 4 wt. %, or at least 4.5 wt. %, or at least 5 wt. %, or at least 5.5 wt. %, or at least 6 wt. %, based on the total weight of the CE fibers and/or not more than about 25 wt. %, or not more than 20 wt. %, or not more than 18 wt. %, or not more than 16 wt. %, or not more than 13 wt. %, or not more than 10 wt. %, or not more than 9 wt. %, or not more than 8 wt. %, or not more than 7 wt. %, based on the weight of the CE fibers, as determined by oven dryness. Suitable ranges include, but are not limited to, 3-20, or 3-18, or 3-16, or 3-13, or 3-10, or 3-9, or 3-8, or 3-7, or 3-6.5, or 4-20, or 4-18, or 4-16, or 4-13, or 4-10, or 4-9, or 4-8, or 4-7, or 4-6.5, or 5-20, or 5-18, or 5-16, or 5-13, or 5-10, or 5-9, or 5-8, or 5-7, or 5.5-20, or 5.5-18, or 5.5-16, or 5.5-13, or 5.5-10, or 5.5-9, or 6-20, or 6-18, or 6-16, or 6-13, or 6-10, in each case as wt. % based on the weight of the CE staple fiber.

The CE fibers have the advantage of not requiring their maintenance as a slurry or emulsion (e.g. greater than 30 wt % water) during shipping as well as reducing shipping weight and its associated costs. Any suitable type of dryer can be used such as, for example, a forced air oven, a drum dryer, or a heat setting channel. The dryer may be operated at any temperature and pressure conditions that provide the requisite level of drying without damaging the yarn.

When the CE fibers are CE staple fibers, once dried, the CE fibers may be fed to a cutting zone without first baling, or may be optionally baled and the resulting bales may be introduced into a cutting zone, wherein the CE fibers in any form, whether yarn or tow band, may be cut into staple fibers. Any suitable type of cutting device may be used that is capable of cutting the filaments to a desired length without excessively damaging the fibers. Examples of cutting devices can include, but are not limited to, rotary cutters, guillotines, stretch breaking devices, reciprocating blades, and combinations thereof. Once cut, the CE fibers may be baled or otherwise bagged or packaged for subsequent transportation, storage, and/or use.

The cut length can be determined by any suitable reliable method. Commonly used optical instruments include the Metso FS-5 and the Optest FQA. The data output of these devices can provide information such as the average length and length distribution curve.

The cut length referred to herein can be the average cut length or the set point on the cutter to designate the target cut length. The CE staple fiber length is generally in the range of at least 1.5 mm and up to 150 mm. Examples of desirable cut lengths include a cut length of at least 2 mm, or at least 2.5 mm, and not more than about 150 mm, or not more than 125 mm, or not more than 100 mm, or not more than 85 mm, or not more than 70 mm, or not more than 60 mm, or not more than 50 mm, or not more than 45 mm, or not more than 40 mm, or not more than 30 mm, or not more than 20 mm, or not more than 15 mm, or not more than 10 mm, or not more than 8 mm, or not more than 7 mm, or not more than 6 mm, or not more than 5 mm, or not more than or less than 4.5 mm, or not more than or less than 4.0 mm, or not more than 3.8 mm, or not more than 3.5 mm, or not more than 3.3 mm. Examples of cut length ranges include from 1.5 to 150 mm, or 1.5 to 100 mm, or 1.5 to 80 mm, or from 1.5 to 60, or from 1.5 to 40, or from about 1.5 to 30, or from 1.5 to 20, or from 0.5 to 15, or from 1.5 to 10, or from 1.5 to 7, or from 1.5 to 6, or from 2 to 6, or from 3 to 6, or from 2.5 to 5, or from 2.5 to 4.5, or from 2.5 to 4, or from 2.5 to less than 4, or from 2.5 to 3.8 mm, in each case in mm.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a cut length within +/−20% of any one of the above stated cut lengths. Alternatively, at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a cut length within +/−15% of any one of the above stated cut lengths; or at least 70%, or at least 80%, or at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a cut length within +/−10% of any one of the above stated cut lengths. Desirably, at least 85%, or at least 90%, or at least 95%, or at least 97% of the CE fibers have a cut length within +/−15%, or within +/−10% of any one of the above stated cut lengths.

The CE fibers are fibers rather than particles. As such, the CE fibers have an aspect ratio (L/D) of at least 1.5:1, or at least 2:1, or at least 2.5:1, or at least 3:1, or at least 3.5:1, or at least 4:1, or at least 5:1, or at least 6:1, or at least 7:1, or at least 8:1, or at least 9:1, or at least 10:1, or at least 20:1, or at least 30:1, or at least 40:1, or at least 50:1.

In one embodiment or in combination with any of the mentioned embodiments, the ratio of CE staple fiber cut length to DPF of the CE staple fibers is less than 80:1, or not more than 70:1, or not more than 60:1, or not more than 50:1, or not more than 40:1, or not more than 35:1, or not more than 30:1, or not more than 20:1, or not more than 15:1, or not more than 10:1, or not more than 8:1, or not more than 5:1, or not more than 4:1, or not more than 3.1, optionally with CE fibers having a cut length of less than 80 mm, or not more than 70 mm, or not more than 60 mm, or not more than 50 mm, or not more than 40 mm, or not more than 30 mm, or not more than 20 mm, or not more than 15 mm, or not more than 10 mm, or not more than 8 mm, or not more than 7 mm, or not more than 6 mm. If short cut CE staple fibers are used, the ratio of cut length:DPF can be not more than 2.95:1, or not more than 2.9:1, or not more than 2.85:1 or not more than 2.8:1 or not more than 2.75:1 or not more than 2.6:1 or not more than 2.5:1 or not more than 2.3:1 or not more than 2.0:1. In one embodiment or in combination with any of the mentioned embodiments, the cut length:DPF is not more than 3.5:1, or not more than 3.3:1, or not more than 3:1, or not more than 2.95:1, or not more than 2.8:1, or not more than 2.5:1 at a cut length of less than 6 mm, or not more than 5 mm, or not more than 4 mm.

In one or any of the embodiments mentioned, the CE fibers can have any one or more of the following features:

-   -   a) a cut length of less than 150 mm, or 80 mm or less, or 40 mm         or less, or not more than 6.0 mm, or 2.0 to 5 mm, or     -   b) an aspect ratio L/D of at least 5:1, or at least 10:1, or     -   c) a cut length:DPF ratio of not more than 40, or not more than         25, or not more than 20, or not more than 15, or not more than         10, or not more than 7, or not more than 3.5, or     -   d) at least 80% of the CE fibers have a cut length within +/−20%         of any one of the above stated cut lengths, or     -   e) any combination of two or more of any of the above.

Any suitable type of cutting device may be used that can cut the filaments to a desired length without excessively damaging the fibers. Examples of cutting devices can include, but are not limited to, rotary cutters, guillotines, stretch breaking devices, reciprocating blades, and combinations thereof. Once cut, the staple fibers may be baled or otherwise bagged or packaged for subsequent transportation, storage, and/or use.

The CE polymers used to make the CE fibers, and the CE fibers, are desirably not chemically treated to alter the chemical structure of the cellulose ester upon or after the cellulose ester is spun into the filament, such as to increase the hydroxyl number of the CE fiber. For example, the CE fibers desirably are not surface hydrolyzed. Surface hydrolysis can increase the number of —OH sites on a cellulose ester. Such a process, however, adds extra processing steps, is economically impractical, and is not needed to provide good cohesive force to the nonwoven web or tensile strength to the fabric when employing the methods described herein.

The nonwoven web and fabric can contain CE fibers in an amount of least 0.25 wt. %, or at least 0.5 wt. %, or at least 0.75 wt. %, or at least 1 wt. %, or at least 2 wt. %, or at least 3 wt. %, or at least 4 wt. %, or at least 5 wt. %, or at least 6 wt. %, or at least 7 wt. %, or at least 8 wt. %, or at least 9 wt. %, or at least 10 wt. %, or at least 12 wt. %, or at least 15 wt. %, or at least 18 wt. %, or at least 20 wt. %, based on the total weight of web or fabric. In addition or in the alternative, the amount of CE fibers in the web and fabric can be up to 100 wt. %, or up to 90 wt. %, or up to 80 wt. %, or up to 75 wt. %, or up to 65 wt. %, or up to 55 wt. %, or up to 50 wt. %, or up to 45 wt. %, or up to 40 wt. %, or up to 35 wt. %, or up to 30 wt. %, or up to 25 wt. %, or up to 20 wt. %, or up to 18 wt. %, or up to 15 wt. %, or up to 12 wt. %, or up to 10 wt. %, or up to 9 wt. %, or up to 8 wt. %, or up to 7 wt. %, or up to 6 wt. %, or up to 5 wt. %, based on the total weight of all fibers in the web and/or fabric.

Examples of suitable ranges of the CE fibers in the nonwoven web/fabric include from 0.75 to 100, or from 1 to 100, or from 3 to 100, or from 5 to 100, or from 5 to 80, or 5 to 70, or from 5 to 55, or 5 to 40, or 5 to 20, or 5 to 15, or from 10 to 100, or from 10 to 80, or 10 to 70, or from 10 to 55, or 10 to 40, or 10 to 20, or from 20 to 100, or from 20 to 80, or 20 to 70, or from 20 to 55, or 20 to 40, or from 30 to 100, or from 30 to 80, or 30 to 70, or from 30 to 55, or 30 to 40, or from 40 to 100, or from 40 to 80, or 40 to 70, or from 40 to 55, or from 50 to 100, or from 0 to 80, or 50 to 70, in each case as a wt. % based on weight of all fibers in the web and/or fabric.

In embodiments, the nonwoven web/fabric may contain CE fibers in an amount of least 15 wt. %, or at least 18 wt. %, or at least 20 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. %, or at least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, or 100%, based on the total weight of binder fibers in the web or fabric. In addition or in the alternative, the amount of CE fibers can be up to 100 wt. %, or up to 95 wt. %, or up to 90 wt. %, or up to 85 wt. %, or up to 80 wt. %, or up to 70 wt. %, or up to 60 wt. %, or up to 50 wt. %, or up to 40 wt. %, or up to 35 wt. %, based on the total weight of all binder fibers in the web and/or fabric.

Examples of suitable ranges of the CE fibers based on the weight of all binder fibers in the nonwoven web/fabric include from 10 to 100, or from 40 to 100, or from 70 to 100, or from 80 to 100, or form 90 to 100, or from 95 to 100, or from 98 to 100, or from 10 to 90, or 40 to 90, or from 60 to 90, or 80 to 90, in each case as a wt. % based on weight of all binder fibers in the web and/or fabric.

Example of other binder fibers which may be in combination with the CE fibers in the nonwoven or fabric include polyesters such as those polyethylene terephthalate (PET), polycyclohexylenedimethylene terephthalate (PCT) and other copolymers, olefinic polymers such as polypropylene and polyethylene of all varieties, polycarbonates, and sulfopolyester fibers.

The CE fibers may also be combined with base fibers, such that the nonwoven web and fabric may contain a combination of binder fibers and base fibers. Base fibers are any fibers other than the binder fibers. Base fibers will not exhibit thermoplastic behavior and will generally thermally degrade rather than exhibit a glass transition temperature. Base fibers can contribute to the desired physical, chemical, or mechanical properties of the nonwoven web or fabric, such as biodegradability, tensile strength, printability or dyeing capabilities, shrinkability, water or air permeability, wicking, and any other characteristics important to the requirements of the application. Examples of base fibers include natural fibers and synthetic fibers. Base synthetic fibers are those fibers that are, at least in part, synthesized or derivatized through chemical reactions, or regenerated, and include, but are not limited to, rayon, viscose, mercerized fibers or other types of regenerated cellulose (conversion of natural cellulose to a soluble cellulosic derivative and subsequent regeneration) such as lyocell (also known as Tencel), Cupro, Modal, acetates such as polyvinylacetate, glass, polyamides including nylon, poly sulfates, poly sulfones, polyethers, polyacrylates, acrylonitrile copolymers, polyvinylchloride (PVC), polylactic acid, polyglycolic acid, and combinations thereof. Base natural fibers include those that are plant derived or animal derived. Examples of plant derived natural fibers include wheat straw, rice straw, hardwood pulp, softwood pulp, and wood flour, wood cellulose, abaca, coir, cotton, flax, hemp, jute, kapok, papyrus, ramie, rattan, vine, kenaf, abaca, henequen, sisal, soy, rice, cereal straw, bamboo, reeds, esparto grass, bagasse, Sabai grass, milkweed floss fibers, pineapple leaf fibers, switch grass, lignin-containing plants, and the like. Examples of animal derived fibers include wool, silk, mohari, cashmere, goat hair, horse hair, avian fibers, camel hair, angora wool, and alpaca wool.

The base fibers, like the binder fibers, can be single-component fibers or multicomponent fibers containing islands in a sea, or sheaths, or discrete domains of two or more polymers.

The source of CE fibers, other binder fibers, or base fibers can be virgin or post-consumer or postindustrial fibers, or a combination thereof. Desirably, in certain embodiments, at least 5 wt. %, or at least 10 wt. %, or at least 15 wt. %, or at least 20 wt. %, or at least 25 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. % of the nonwoven web or fabric contains post-consumer or postindustrial fibers. Desirably, at least 5 wt. %, or at least 10 wt. %, or at least 15 wt. %, or at least 20 wt. %, or at least 25 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. % of the CE fibers, or of the binder fibers, are post-consumer or post industrial fibers.

In one embodiment or in combination with any of the mentioned embodiments, the binder fibers are present in an amount of at least 15 wt. %, or at least 18 wt. %, or at least 20 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. %, or at least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, or 100%, based on the total weight of the nonwoven web or fabric. In addition or in the alternative, the amount of binder fibers can be up to 100 wt. %, or up to 95 wt. %, or up to 90 wt. %, or up to 85 wt. %, or up to 80 wt. %, or up to 70 wt. %, or up to 60 wt. %, or up to 50 wt. %, or up to 40 wt. %, or up to 35 wt. %, based on the total weight of the nonwoven web or fabric.

In one embodiment or in combination with any of the mentioned embodiments, the base fibers are present in an amount of at least 10 wt. %, or at least 12 wt. %, or at least 15 wt. %, or at least 18 wt. %, or at least 20 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 50 wt. %, or at least 60 wt. %, or at least 70 wt. %, or at least 80 wt. %, or at least 90 wt. %, or at least 95 wt. %, or 100%, based on the total weight of the nonwoven web or fabric. In addition or in the alternative, the amount of base fibers can be up to 85 wt. %, or up to 80 wt. %, or up to 70 wt. %, or up to 60 wt. %, or up to 50 wt. %, or up to 40 wt. %, or up to 35 wt. %, based on the total weight of the nonwoven web or fabric.

The weight ratio of CE fibers to all other synthetic fibers can be least 0.1:1, or at least 0.5:1, or at least 0.7:1, or at least 1:1, or at least 1.5:1, or at least 2:1, or at least 3:1, or at least 4:1, or at least 5:1, or at least 7:1, or at least 8:1, or at least 10:1, or at least 15:1, or at least 20:1, or at least 30:1, or at least 40:1.

In one embodiment or in combination with any of the mentioned embodiments, the nonwoven webs/fabrics contain at least 55 wt. % fibers, or at least 60 wt. % fibers, or at least 70 wt. % fibers, or at least 80 wt. % fibers, or at least 85 wt. % fibers, or at least 90 wt. % fibers, or at least 95 wt. % fibers, or at least 96 wt. % fibers, or at least 97 wt. % fibers, or at least 98 wt. % fibers, or at least 99 wt. % fibers, or at least 99.5 wt. % fibers, or at least 99.75 wt. % fibers, or at least 99.8 wt. % fibers, or at least 99.9 wt. % fibers, based on the dry weight of the wet laid web or article. These fibers are any fibrous material in the nonwoven web/fabric.

In another embodiment or in any of described embodiments, the CE fibers, and depending on the nature of the other fibers if present, the nonwoven web and/or fabric can be biodegradable, meaning that such CE fibers are expected to decompose under certain environmental conditions. The degree of degradation can be characterized by the weight loss of a sample over a given period of exposure to certain environmental conditions. In some cases, the CE fibers, or the webs and/or fabrics containing or the CE fibers can exhibit a weight loss of at least about 5, 10, 15, or 20 percent after burial in soil for 60 days and/or a weight loss of at least about 15, 20, 25, 30, or 35 percent after 15 days of exposure in a composter. However, the rate of degradation may vary depending on the particular end use of the fibers, as well as the composition of the wet laid product, and the specific test. Exemplary test conditions are provided in U.S. Pat. Nos. 5,870,988 and 6,571,802, incorporated herein by reference.

The CE fibers and webs/fabrics containing the CE fibers can also exhibit enhanced levels of environmental non-persistence, characterized by better-than-expected degradation under various environmental conditions. Fibers and fibrous nonwoven articles can meet or exceed passing standards set by international test methods and authorities for industrial compostability, home compostability, and/or soil biodegradability.

To be considered “compostable,” a material must meet the following four criteria: (1) the material must be biodegradable; (2) the material must be disintegrable; (3) the material must not contain more than a maximum amount of heavy metals; and (4) the material must not be ecotoxic. As used herein, the term “biodegradable” generally refers to the tendency of a material to chemically decompose under certain environmental conditions.

Biodegradability is an intrinsic property of the material itself, and the material can exhibit different degrees of biodegradability, depending on the specific conditions to which it is exposed. The term “disintegrable” refers to the tendency of a material to physically decompose into smaller fragments when exposed to certain conditions. Disintegration depends both on the material itself, as well as the physical size and configuration of the article being tested. Ecotoxicity measures the impact of the material on plant life, and the heavy metal content of the material is determined according to the procedures laid out in the standard test method.

In one embodiment or in combination with any of the mentioned embodiments or in any of the mentioned embodiments, the CE fibers, and the webs/fabrics containing the CE fibers, are industrially compostable, home compostable, or both. In this or on any of the embodiment, the CE fibers used, or the webs/fabrics containing the CE fibers, can satisfy four criteria:

-   -   1) biodegrade in that at least 90% carbon content is converted         within 180 days;     -   2) disintigratable in that least 90% the material disintegrates         within 12 weeks;     -   3) does not contain heavy metals beyond the thresholds         established under the EN12423 standard; and     -   4) the disintegrated content supports future plant growth as         humus; where each of these four conditions are tested per the         ASTM D6400, or ISO 17088, or EN 13432 method.

The CE fibers, and the webs/fabrics containing the CE fibers can exhibit a biodegradation of at least 70 percent in a period of not more than 50 days, when tested under aerobic composting conditions at ambient temperature (28° C.±2° C.) according to ISO 14855-1 (2012). In some cases, the CE fibers, and the webs/fabrics containing the CE fibers, can exhibit a biodegradation of at least 70 percent in a period of not more than 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, or 37 days when tested under these conditions, also called “home composting conditions.” These conditions may not be aqueous or anaerobic. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers, can exhibit a total biodegradation of at least about 71, or at least 72, or at least 73, or at least 74, or at least 75, or at least 76, or at least 77, or at least 78, or at least 79, or at least 80, or at least 81, or at least 82, or at least 83, or at least 84, or at least 85, or at least 86, or at least 87, or at least 88 percent, when tested under according to ISO 14855-1 (2012) for a period of 50 days under home composting conditions. This may represent a relative biodegradation of at least about 95, or at least 97, or at least 99, or at least 100, or at least 101, or at least 102, or at least 103 percent, when compared to cellulose subjected to identical test conditions.

To be considered “biodegradable,” under home composting conditions according to the French norm NF T 51-800 and the Australian standard AS 5810, a material must exhibit a biodegradation of at least 90 percent in total (e.g., as compared to the initial sample), or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradation under home compositing conditions is 1 year. The CE fibers, and/or the webs/fabrics containing the CE fibers and the products made thereby, may exhibit a biodegradation of at least 90 percent within not more than 1 year, measured according 14855-1 (2012) under home composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers, may exhibit a biodegradation of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, 9 or at least 8, or at least 99, or at least 99.5 percent within not more than 1 year, or the fibers may exhibit 100 percent biodegradation within not more than 1 year, measured according 14855-1 (2012) under home composting conditions.

Additionally, or in the alternative, the CE fibers, and/or the webs/fabrics containing the CE fibers, may exhibit a biodegradation of at least 90 percent within not more than about 350, or not more than 325, or not more than 300, or not more than 275, or not more than 250, or not more than 225, or not more than 220, or not more than 210, or not more than 200, or not more than 190, or not more than 180, or not more than 170, or not more than 160, or not more than or not more than 150, or not more than 140, or not more than 130, or not more than 120, or not more than 110, or not more than 100, or not more than 90, or not more than 80, or not more than 70, or not more than 60, or not more than 50 days, measured according 14855-1 (2012) under home composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers, can be at least about 97, or at least 98, or at least 99, or at least 99.5 percent biodegradable within not more than about 70, or not more than 65, or not more than 60, or not more than 50 days of testing according to ISO 14855-1 (2012) under home composting conditions. As a result, the CE fibers, and/or the webs/fabrics containing the CE fibers may be considered biodegradable according to, for example, French Standard NF T 51-800 and Australian Standard AS 5810 when tested under home composting conditions.

The CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a biodegradation of at least 60 percent in a period of not more than 45 days, when tested under aerobic composting conditions at a temperature of 58° C. (±2° C.) according to ISO 14855-1 (2012). In some cases, they can exhibit a biodegradation of at least 60 percent in a period of not more than 44, or not more than 43, or not more than 42, or not more than 41, or not more than 40, or not more than 39, or not more than 38, or not more than 37, or not more than 36, or not more than 35, or not more than 34, or not more than 33, or not more than 32, or not more than 31, or not more than 30, or not more than 29, or not more than 28, or not more than 27 days when tested under these conditions, also called “industrial composting conditions.” These may not be aqueous or anaerobic conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a total biodegradation of at least about 65, or at least 70, or at least 75, or at least 80, or at least 85, or at least 87, or at least 88, or at least 89, or at least 90, or at least 91, or at least 92, or at least 93, or at least 94, or at least 95 percent, when tested under according to ISO 14855-1 (2012) for a period of 45 days under industrial composting conditions. This may represent a relative biodegradation of at least about 95, or at least 97, or at least 99, or at least 100, or at least 102, or at least 105, or at least 107, or at least 110, or at least 112, or at least 115, or at least 117, or at least 119 percent, when compared to cellulose fibers subjected to identical test conditions.

To be considered “biodegradable,” under industrial composting conditions according to ASTM D6400 and ISO 17088, at least 90 percent of the organic carbon in the whole item (or for each constituent present in an amount of more than 1% by dry mass) must be converted to carbon dioxide within 180 days. According to European standard ED 13432 (2000), a material must exhibit a biodegradation of at least 90 percent in total, or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradability under industrial compositing conditions is 180 days. The CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of at least 90 percent within not more than 180 days, measured according 14855-1 (2012) under industrial composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5 percent within not more than 180 days, or the fibers may exhibit 100 percent biodegradation within not more than 180 days, measured according 14855-1 (2012) under industrial composting conditions.

Additionally, or in the alternative, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of least 90 percent within not more than about 175, or not more than 170, or not more than 165, or not more than 160, or not more than 155, or not more than 150, or not more than 145, or not more than 140, or not more than 135, or not more than 130, or not more than 125, or not more than 120, or not more than 115, or not more than 110, or not more than 105, or not more than 100, or not more than 95, or not more than 90, or not more than 85, or not more than 80, or not more than 75, or not more than 70, or not more than 65, or not more than 60, or not more than 55, or not more than 50, or not more than 45 days, measured according 14855-1 (2012) under industrial composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can be at least about 97, 98, 99, or 99.5 percent biodegradable within not more than about 65, or not more than 60, or not more than 55, or not more than 50, or not more than 45 days of testing according to ISO 14855-1 (2012) under industrial composting conditions. As a result, the CE fibers, and/or the webs/fabrics containing the CE fibers may be considered biodegradable according ASTM D6400 and ISO 17088 when tested under industrial composting conditions.

The CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a soil biodegradation of at least 60 percent within not more than 130 days, measured according to ISO 17556 (2012) under aerobic conditions at ambient temperature. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a biodegradation of at least 60 percent in a period of not more than 130, or not more than 120, or not more than 110, or not more than 100, or not more than 90, or not more than 80, or not more than 75 days when tested under these conditions, also called “soil composting conditions.” These may not be aqueous or anaerobic conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a total biodegradation of at least about 65, or at least 70, or at least 72, or at least 75, or at least 77, or at least 80, or at least 82, or at least 85 percent, when tested under according to ISO 17556 (2012) for a period of 195 days under soil composting conditions. This may represent a relative biodegradation of at least about 70, or at least 75, or at least 80, or at least 85, or at least 90, or at least 95 percent, when compared to cellulose fibers subjected to identical test conditions.

In order to be considered “biodegradable,” under soil composting conditions according the OK biodegradable SOIL conformity mark of Vinçotte and the DIN Geprüft Biodegradable in soil certification scheme of DIN CERTCO, a material must exhibit a biodegradation of at least 90 percent in total (e.g., as compared to the initial sample), or a biodegradation of at least 90 percent of the maximum degradation of a suitable reference material after a plateau has been reached for both the reference and test item. The maximum test duration for biodegradability under soil compositing conditions is 2 years. The CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of at least 90 percent within not more than 2 years, 1.75 years, 1 year, 9 months, or 6 months measured according ISO 17556 (2012) under soil composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5 percent within not more than 2 years, or the fibers may exhibit 100 percent biodegradation within not more than 2 years, measured according ISO 17556 (2012) under soil composting conditions.

Additionally, or in the alternative, CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a biodegradation of at least 90 percent within not more than about 700, 650, 600, 550, 500, 450, 400, 350, 300, 275, 250, 240, 230, 220, 210, 200, or 195 days, measured according 17556 (2012) under soil composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can be at least about 97, or at least 98, or at least 99, or at least 99.5 percent biodegradable within not more than about 225, or not more than 220, or not more than 215, or not more than 210, or not more than 205, or not more than 200, or not more than 195 days of testing according to ISO 17556 (2012) under soil composting conditions. As a result, the CE fibers, and/or the webs/fabrics containing the CE fibers may meet the requirements to receive The OK biodegradable SOIL conformity mark of Vinçotte and to meet the standards of the DIN Geprüft Biodegradable in soil certification scheme of DIN CERTCO.

In some cases, CE fibers, and/or the webs/fabrics containing the CE fibers may include less than 1, or not more than 0.75, or not more than 0.50, or not more than 0.25 weight percent of components of unknown biodegradability, based on the weight of the CE staple fiber. In some cases, the fibers or fibrous wet laid articles described herein may include no components of unknown biodegradability.

In addition to being the CE fibers being biodegradable under industrial and/or home composting conditions, the webs/fabrics, including wet laid non-woven articles may also be compostable under home and/or industrial conditions. As described previously, a material is considered compostable if it meets or exceeds the requirements set forth in EN 13432 for biodegradability, ability to disintegrate, heavy metal content, and ecotoxicity. The CE fibers or fibrous wet laid articles described herein may exhibit sufficient compostability under home and/or industrial composting conditions to meet the requirements to receive the OK compost and OK compost HOME conformity marks from Vinçotte.

In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers and the products made thereby, may have a volatile solids concentration, heavy metals and fluorine content that fulfill all of the requirements laid out by EN 13432 (2000). Additionally, the CE fibers may not cause a negative effect on compost quality (including chemical parameters and ecotoxicity tests).

In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a disintegration of at least 90 percent within not more than 26 weeks, measured according to ISO 16929 (2013) under industrial composting conditions. In some cases, the fibers or fibrous wet laid articles may exhibit a disintegration of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5 percent under industrial composting conditions within not more than 26 weeks, or the fibers or wet laid articles may be 100 percent disintegrated under industrial composting conditions within not more than 26 weeks. Alternatively, or in addition, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a disintegration of at least 90 percent under industrial compositing conditions within not more than about 26, or not more than 25, or not more than 24, or not more than 23, or not more than 22, or not more than 21, or not more than 20, or not more than 19, or not more than 18, or not more than 17, or not more than 16, or not more than 15, or not more than 14, or not more than 13, or not more than 12, or not more than 11, or not more than 10 weeks, measured according to ISO 16929 (2013). In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may be at least 97, or at least 98, or at least 99, or at least 99.5 percent disintegrated within not more than 12, or not more than 11, or not more than 10, or not more than 9, or not more than 8 weeks under industrial composting conditions, measured according to ISO 16929 (2013).

In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers can exhibit a disintegration of at least 90 percent within not more than 26 weeks, measured according to ISO 16929 (2013) under home composting conditions. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a disintegration of at least about 91, or at least 92, or at least 93, or at least 94, or at least 95, or at least 96, or at least 97, or at least 98, or at least 99, or at least 99.5 percent under home composting conditions within not more than 26 weeks, or the fibers or wet laid articles may be 100 percent disintegrated under home composting conditions within not more than 26 weeks. Alternatively, or in addition, the CE fibers, and/or the webs/fabrics containing the CE fibers may exhibit a disintegration of at least 90 percent within not more than about 26, or not more than 25, or not more than 24, or not more than 23, or not more than 22, or not more than 21, or not more than 20, or not more than 19, or not more than 18, or not more than 17, or not more than 16, or not more than 15 weeks under home composting conditions, measured according to ISO 16929 (2013). In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may be at least 97, or at least 98, or at least 99, or at least 99.5 percent disintegrated within not more than 20, or not more than 19, or not more than 18, or not more than 17, or not more than 16, or not more than 15, or not more than 14, or not more than 13, or not more than 12 weeks, measured under home composting conditions according to ISO 16929 (2013).

The nonwoven webs and fabrics containing the CE fibers can achieve higher levels of biodegradability and/or compostability without use of additives that have traditionally been used to facilitate environmental non-persistence of similar fibers. Such additives can include, for example, photodegradation agents, biodegradation agents, decomposition accelerating agents, and various types of other additives. Despite being substantially free of these types of additives, the CE fibers, and/or the webs/fabrics containing the CE fibers have been found to exhibit enhanced biodegradability and compostability when tested under industrial, home, and/or soil conditions, as discussed previously.

In some embodiments, the CE fibers, and/or the webs/fabrics containing the CE fibers may be substantially free of photodegradation agents added when the CE fibers are combined with the other fibers, or added to the web or fabric. Optionally, one of the CE fibers themselves, or any combination thereof, may contain not more than about 1, or not more than 0.75, or not more than 0.50, or not more than 0.25, or not more than 0.10, or not more than 0.05, or not more than 0.025, or not more than 0.01, or not more than 0.005, or not more than 0.0025, or not more than 0.001 weight percent of photodegradation agent, based on the total weight of the fiber, or the CE fibers may include no photodegradation agents. Examples of such photodegradation agents include, but are not limited to, pigments which act as photooxidation catalysts and are optionally augmented by the presence of one or more metal salts, oxidizable promoters, and combinations thereof. Pigments can include coated or uncoated anatase or rutile titanium dioxide, which may be present alone or in combination with one or more of the augmenting components such as, for example, various types of metals. Other examples of photodegradation agents include benzoins, benzoin alkyl ethers, benzophenone and its derivatives, acetophenone and its derivatives, quinones, thioxanthones, phthalocyanine and other photosensitizers, ethylene-carbon monoxide copolymer, aromatic ketone-metal salt sensitizers, and combinations thereof.

In some embodiments, the CE fibers, and/or the webs/fabrics containing the CE fibers may be substantially free of biodegradation agents and/or decomposition agents other than plasticizers. For example, the CE fibers, and/or the webs/fabrics containing the CE fibers may include not more than about 1, or not more than 0.75, or not more than 0.50, or not more than 0.25, or not more than 0.10, or not more than 0.05, or not more than 0.025, or not more than 0.01, or not more than 0.005, or not more than 0.0025, or not more than 0.0020, or not more than 0.0015, or not more than 0.001, or not more than 0.0005 weight percent of biodegradation agents and/or decomposition agents, other than plasticizers, based on the total weight of the fiber, or the fibers may include no biodegradation and/or decomposition agents. Examples of such biodegradation and decomposition agents include, but are not limited to, salts of oxygen acid of phosphorus, esters of oxygen acid of phosphorus or salts thereof, carbonic acids or salts thereof, oxygen acids of phosphorus, oxygen acids of sulfur, oxygen acids of nitrogen, partial esters or hydrogen salts of these oxygen acids, carbonic acid and its hydrogen salt, sulfonic acids, and carboxylic acids.

Other examples of such biodegradation and decomposition agents include an organic acid selected from the group consisting of oxo acids having 2 to 6 carbon atoms per molecule, saturated dicarboxylic acids having 2 to 6 carbon atoms per molecule, and lower alkyl esters of said oxo acids or said saturated dicarboxylic acids with alcohols having from 1 to 4 carbon atoms. Biodegradation agents may also comprise enzymes such as, for example, a lipase, a cellulase, an esterase, and combinations thereof. Other types of biodegradation and decomposition agents can include cellulose phosphate, starch phosphate, calcium secondary phosphate, calcium tertiary phosphate, calcium phosphate hydroxide, glycolic acid, lactic acid, citric acid, tartaric acid, malic acid, oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, acetic acid, and combinations thereof.

The CE fibers, and/or the webs/fabrics containing the CE fibers may also be substantially free of several other types of additives that have been added to other synthetic fibers to encourage environmental non-persistence. Examples of these additives can include, but are not limited to, enzymes, microorganisms, water soluble polymers, water-dispersible additives, nitrogen-containing compounds, hydroxy-functional compounds, oxygen-containing heterocyclic compounds, sulfur-containing heterocyclic compounds, anhydrides, monoepoxides, and combinations thereof. In some cases, the CE fibers, and/or the webs/fabrics containing the CE fibers may include not more than about 0.5, or not more than 0.4, or not more than 0.3, or not more than 0.25, or not more than 0.1, or not more than 0.075, or not more than 0.05, or not more than 0.025, or not more than 0.01, or not more than 0.0075, or not more than 0.005, or not more than 0.0025, or not more than 0.001 weight percent of these types of additives, based on the weight of the CE fibers, or based on the weight of all fibers. The CE fibers may be free of the addition of any of these types of additives.

In an example, the nonwoven or fabric can be compostable in industrial environment (in accordance with EN 13432 or ASTM D6400) meeting the following four criteria:

-   -   1. Biodegradation determined by measuring the carbon dioxide         produced by the sample under controlled composting conditions         following ISO 14855-1:2012, where the sample is mixed with         compost and placed in a bioreactor at 58° C. under continuous         flow of humidified air. At the exit, the CO₂ concentration is         measured and related to the theoretical amount that could be         produced regarding the carbon content of the sample.     -   2. Disintegration as evaluated on a pilot-scale by simulating a         real composting environment following ISO 16929:2013, where the         samples in their final form are mixed with fresh artificial         bioresidue. Oxygen concentration, temperature and humidity are         regularly controlled. After 12 weeks, the resulting composts are         sieved and the remaining amount of material in pieces >2 mm, if         any, is determined.     -   3. Ecotoxicity of the resulting compost is evaluated in plants         following OECD 208 (2006), where the sample material in powder         form is added to a bioreactor with fresh bioresidue following         the same procedure as in the disintegration test. A comparison         is made with the compost resulting from blank bioreactors and         bioreactors containing the material tested with regards to plant         seedling emergence and growth. Both parameters higher than 90%         with respect to the blank compost passes the test.     -   4. Lacking metals, where each product is identified and         characterized including at least: Information and identification         of the constituents, presence of regulated metals (Zn, Cu, Ni,         Cd, Pb, Hg, Cr, Mo, Se, As, Co) and other hazardous substances         to the environment (F), and content in total dry and volatile         solids.

The webs/fabrics described in embodiment can also be compostable in industrial and backyard or home composting conditions.

Compostability of CE fibers with a DS of 2.5 or below can be achieved without adding any biodegradation and decomposition agents, e.g. hydrolysis assistant or any intentional degradation promoter additives.

The webs/fabrics can be biodegradable in soil medium in accordance with ISO 17556:2003 testing protocol.

If desired, biodegradation and decomposition agents, e.g. hydrolysis assistant or any intentional degradation promoter additives can be added to a web or fabric or be contained within the CE fibers. The decomposition agent can be chosen in such a way that it does not impact the article shelf-life or does not impact the plant-growth when it is a part of the soil. Those additives can promote hydrolysis by releasing acidic or basic residues, and/or accelerate photo or oxidative degradation and/or promote the growth of selective microbial colony to aid the disintegration and biodegradation in compost and soil medium. In addition to promoting the degradation, these additives can have an additional function such as improving the processability of the article or improving mechanical properties.

Examples of decomposition agents include inorganic carbonate, synthetic carbonate, nepheline syenite, talc, magnesium hydroxide, aluminum hydroxide, diatomaceous earth, natural or synthetic silica, calcined clay, and the like. If used, it is desirable that these fillers are dispersed well in the polymer matrix. The fillers can be used singly, or in a combination of two or more.

Examples of aromatic ketones used as an oxidative decomposition agent include benzophenone, anthraquinone, anthrone, acetylbenzophenone, 4-octylbenzophenone, and the like. These aromatic ketones may be used singly, or in a combination of two or more.

Examples of the transition metal compound used as an oxidative decomposition agent include salts of cobalt or magnesium, preferably aliphatic carboxylic acid (C12 to C20) salts of cobalt or magnesium, and more preferably cobalt stearate, cobalt oleate, magnesium stearate, and magnesium oleate. These transition metal compounds can be used singly, or in a combination of two or more.

Examples of rare earth compounds used as an oxidative decomposition agent include rare earths belonging to periodic table Group 3A, and oxides thereof. Specific examples thereof include cerium (Ce), yttrium (Y), neodymium (Nd), rare earth oxides, hydroxides, rare earth sulfates, rare earth nitrates, rare earth acetates, rare earth chlorides, rare earth carboxylates, and the like. More specific examples thereof include cerium oxide, ceric sulfate, ceric ammonium Sulfate, ceric ammonium nitrate, cerium acetate, lanthanum nitrate, cerium chloride, cerium nitrate, cerium hydroxide, cerium octylate, lanthanum oxide, yttrium oxide, Scandium oxide, and the like. These rare earth compounds may be used singly, or in a combination of two or more.

Examples of basic additives selected can be at least one basic additive chosen from alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkali metal carbonates, alkali metal bicarbonates, ZηO and basic Al2O3. Preferably, the at least one basic additive is selected from the group consisting of MgO, Mg(OH)2, MgCO3, CaO, Ca(OH)2, CaCO3, NaHCO₃, Na2CO3, K2CO3, ZηO KHCO3 and basic Al2O3. In another preferred aspect, the at least one basic additive is selected from the group consisting of MgO, Mg(OH)2, MgCO3, CaO, Ca(OH)2, NaHCO₃, K2CO3, ZηO, KHCO3 and basic Al₂O₃. More preferably, the at least one basic additive is selected from the group consisting of MgO, Mg(OH)2, CaO, Ca(OH)2, ZηO, and basic Al₂O₃. In one aspect, alkaline earth metal oxides, ZηO and basic Al₂O₃ are particularly preferred as basic additive; thus, the at least one basic additive is more preferably selected from the group consisting of MgO, ZηO, CaO and Al₂O₃, and even more preferably from the group consisting of MgO, CaO and ZηO. MgO is the most preferred basic additive.

Examples of organic acid additives include acetic acid, propionic acid, butyric acid, valeric acid, citric acid, tartaric acid, oxalic acid, malic acid, benzoic acid, maleic acid, phthalic acid, and combinations thereof.

As noted above, the nonwoven web contains binder fibers and base fibers. The method for making the nonwoven web is any conventional or exotic method, including spun bond or laced, dry laid, flash spun, and melt blowing processes. In a dry laid process, a compressed bale of fibers is opened, and the fibers are withdrawn and opened with opening equipment and made into a batt that is fed into equipment for making the nonwoven web, such as a carding or air laid machine.

Dry laid processes include air laying and carding. An example of a dry laid process includes fiber preparation, blending of fibers, carding, and garneting. In the dry laid process, the fibers can be collected into a web form by parallel lapping, cross lapping, or air laying lap forming. Bats can be formed by laying carded webs over each other. Cross or parallel lapped webs are not considered laminates as used herein.

Spun bond processes form a web from filaments immediately as they exit the extruder. Molten thermoplastic material is extruded through capillaries in spinneret as continuous filaments with the diameter substantially that of the spinneret holes. The fibers are cooled by an eductive or other drawing method. To form the nonwoven web, the spunbond filaments are randomly deposited onto a surface such as a screen or belt to form a loosely entangled web, which is then bonded by any thermal bonding technique, such as hot roll calendaring, through air bonding, or by steam bonding at elevated pressure.

Melt blown is accomplished by extruding molten polymer though very fine capillaries in a spin die or net as filaments that are partially cooled with high velocity hot air as they fall from the die head, thereby reducing their diameter. These fibers are typically finer than spun bond fibers and are often added to spun bond fibers to form SM (spun-melt) or SMS (spun-melt-spun) webs. Desirably, the nonwoven web is a dry laid nonwoven web, and in particular, an SM or SMS web or a carded or cross-lapped nonwoven web.

Binder fibers may contain a plasticizer in an amount suitable to provide a bonded fabric with the desired bond strength or other property.

The basis weight of the nonwoven web can be at least 8 g/m², or at least 10 g/m², or at least 13 g/m², or at least 15 g/m², or at least 18 g/m², or at least 20 g/m², or at least 23 g/m², or at least 25 g/m², or at least 27 g/m², or at least 30 g/m², or at least 35 g/m², or at least 40 g/m², or at least 45 g/m², or at least 50 g/m². In addition or in the alternative, the basis weight of the nonwoven web is generally not more than 750 g/m², or not more than 600 g/m², or not more than 500 g/m², or not more than 400 g/m², or not more than 250 g/m², or not more than 200 g/m², or not more than 150 g/m², or not more than 100 g/m², or not more than 80 g/m², or not more than 60 g/m², or not more than 50 g/m², or not more than 45 g/m², or not more than 40 g/m², or not more than 37 g/m², or not more than 35 g/m², or not more than 33 g/m², or not more than 30 g/m², or not more than 28 g/m², or not more than 25 g/m², or not more than 23 g/m², or not more than 20 g/m², or not more than 18 g/m².

The nonwoven web can be thermally bonded to make a fabric using ultrasonic bonding. The nonwoven webs have sufficient integrity to allow their passage as a web through the thermal bonding process. In one embodiment or in combination with any of the mentioned embodiments, the nonwoven web, e.g., made by a dry laid or air laid process, has sufficiently entangled fibers to provide a cohesive web that allows it to be thermally bonded to make the fabric without the necessity for any other bonding techniques applied to the web. In embodiments, the web can be prepared using typical bonding techniques applied to the nonwoven web prior to thermal bonding include chemical bonding such as through adhesives or latex bonding or binder powders, solvent fusion, hydroentanglement, or stitching. In some embodiments, the use of bonding additives, such as adhesives, binders and solvents are not used. The nonwoven web can also be needle punched or tacked or tufted to improve handling if needed. In one embodiment or in combination with any of the mentioned embodiments, the nonwoven web, and/or the fabric is hydroentangled, but is not bonded with an adhesive or does not contain or have applied binder powders or thermoplastic sheets or films, or is not solvent fused, or is not stitched, or any combination of the foregoing.

The thermal bonding of the nonwoven web can be accomplished by ultrasonic bonding. Ultrasonic bonding causes the binder fibers to bond to each other and to the other fibers in the web. The bonds will occur at the intersection of the different fibers and are fixed in place once the bonding point cools. The thermal bonding technique does not rely upon a chemical reactions between the base fibers and binder fibers to create the bond.

The thermal bonding technique can be conducted by ultrasonic bonding, in which friction generated by ultrasound causes the cellulose ester fibers to bond to each other and other fibers at their contact points. The nonwoven web can be passed under pressure between the anvil and sonotrode (or horn) operating at the desired frequency, such as at least 10 kHz-80 kHz, or from 15 kHz-70 kHz, or from 15 kHz-50 kHz, or from 15 kHz-45 kHz, or from 15 kHz-35 kHz, or from 15 kHz-30 kHz, or from 15 kHz-20 kHz. Desirably, the welder is a vibrational bonder. The vibrational energy caused by the ultrasonic frequencies causes localized softening or melting of the CE fibers at the joint, resulting in a bond when the vibrational energy is removed and the localized area is cooled. The method employed can be a plunging method whereby the horn plunges toward the web and transmits the ultrasonic vibrations to the web. This method is particularly useful to make a point bonded fabric. Alternatively, the ultrasonic welding can be continuous, which is useful for sealing or creating a larger continuous area of bonding to the fabric, or a scanning method, or a rotary horn welding method, or a traverse welding method. The acoustic energy can be applied at low amplitudes, in the range of 20 microns to 150 microns, by typically would be at 25 to 100 microns. The pressure between the anvil and horn can be from 20 psi to 1000 psi, although higher pressures in excess of 1000 psi (e.g. 1000-6000 psi) can be employed depending on line speed, basis weight, material type, and welding method employed. The height, pattern, shape, and spacing of the projections on the anvil will be determined in part by the desired bonding area, the desired pattern on the fabric, and the basis weight and thickness of the web. Suitable bonding areas and basis weights are described above.

The number of bonding points per square inch created by ultrasonic bonding is not particularly limited, and can include at least 10, or at least 20, or at least 40, or at least 50, or at least 70, or at least 90, or at least 100, or at least 130, or at least 150, or at least 175, or at least 200, or at least 225, and up to 700, or up to 600, or up to 500, or up to 400, or up to 350, or up to 300, or up to 275, or up to 250, or up to 225, or up to 200, or up to 175, or up to 150, in each case points per square inch. Examples of ranges are from 10-600, or from 20-500, or from 10-400, or from 10-300, or from 50-250, or from 100-250, in each case points per square inch.

In one embodiment or in combination with any of the mentioned embodiments, at least 10%, or at least 25%, or at least 50%, or at least 75%, or at least 80%, or at least 90%, or at least 95%, or at least 100% of the seam, point, or pattern bonds created are destructive bonds, meaning that the surrounding non-bonded web tears or separates before the bond delaminates or tears.

The line speed can be any line speed adapted to provide maximum output at the applied calendar roll temperatures, nip pressure, and basis weight to effect thermal bonding, e.g., ultrasonic bonding. Line speeds of at least 10 m/min, or at least 30, or at least 40, or at least 50, or at least 80, or at least 100, or desirably at least 150, or at least 200, or at least 250, or at least 300, or at least 400, or at least 500, or at least 600, or at least 700, in each case as meters/minute are suitable, with the particular line speed selected being dependent on the types of fibers, equipment design, basis weight and thickness of the web, roll temperatures, and other process variables.

The basis weight of the nonwoven webs that can be processed can be at least 10, or at least 15, or at least 20, or at least 30, or at least 35, or at least 40, or at least 45, or at least 50, or at least 55, or at least 60, or at least 65, or at least 70, or at least 75, or at least 80, or at least 85, or at least 90, and in addition or in the alternative, up to 500, or up to 450, or up to 400, or up to 350, or up to 300, or up to 250, or up to 200, or up to 175, or up to 150, or up to 125, or up to 100, or up to 175, or up to 150, or up to 100, or up to 90, or up to 80, or up to 70, or up to 60, or up to 50, or up to 40, or up to or less than 35, or up to 33, or up to 30, or up to 28, or up to 25, or up to 23, or up to 20, or up to 18, or up to 16, in each case grams per m2 (gsm). Examples of ranges include 10-500, or 10-300, or 10-200, or 10-150, or 10-100, or 10-90, or 10-70, or 10-60, or 10-50, or 10-45, or 10-40, or 10-35, or 10-33, or 10-30, or 10-28, or 10-25, or 28-500, or 30-500, or 33-500, or 35-500, or 35-250, or 35-200, or 35-150, or 35-100, in each case in gsm.

In one embodiment or in combination with any of the mentioned embodiments, low basis weight nonwoven webs can be thermally bonded to a significant bond strength via ultrasonic bonding. In embodiments, ultrasonic bonding can be used to bond a nonwoven web to itself or to another nonwoven web (e.g., having a similar composition) and create a bond, such as a seam or more comprehensive lamination, having a break strength that is at least 30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 100% of the break strength of a single stitch seam, or even a destructive bond, and this can be accomplished in the absence of adhesives or binder powders. This is particularly advantageous for delicate nonwoven webs, such as those having a basis weight of 35 gsm or less, or even 32 gsm or less, or 30 gsm or less, or 28 gsm or less, or 25 gsm or less, or 23 gsm or less, or 20 gsm of less. The destructive bond is one in which the surrounding nonbonded web will tear before or rather than the thermally bonded portion of the web delaminating.

In one embodiment or in combination with any of the mentioned embodiments, the nonwoven web and fabrics do not contain a film or are not process with a film or sheet of non-fibrous material. In one embodiment or in combination with any of the mentioned embodiments, the nonwoven web or the fabrics, or any combination or the foregoing, are not a laminate or laminated.

In one embodiment or in combination with any of the mentioned embodiments, the fabric is a nonwoven web containing thermally bonded fibers at discrete bonding portions or discrete bonded points. Desirably, the thermally bonded portions or points are fibers fused at their intersections. The fabric contains a plurality of bonded and unbonded portions in which the bonded portions are discontinuous from each other and the unbonded portions are contiguous to each other. For example, at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 98%, or at least 99% of the number of bonded portions are discontinuous from each other, and alternatively or in addition, at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 98%, or at least 99% of the surface area of the unbonded portions are contiguous to each other, in each case by surface area.

In one embodiment or in combination with any of the mentioned embodiments, the ratio of the cumulative surface area of unbonded portions to the cumulative surface area of bonded portions can be at least 1:1, or at least 2:1, or at least 3:1, or at least 4:1, or at least 5:1, or at least 5.5:1, or at least 6:1, or at least 6.5:1, or at least 7:1, and can go up to 100:1, or 90:1, or 80:1, or 70:1, or 60:1, or 50:1, or 40:1, or 30:1, or 20:1, or 15:1, or 13:1, or 10:1, or 9:1, or 8:1, or 7:1, or 6:1, or 5:1, or 4:1, or 3:1, or 2:1.

In one embodiment or in combination with any of the mentioned embodiments, the thickness of the unbonded portion is greater than the thickness of the bonded portions. Desirably, the top surface of the bonded portions is recessed relative to the top surface of the unbonded portions. In one embodiment or in combination with any of the mentioned embodiments, the top and bottom surfaces of the bonded portions are recessed relative to the corresponding top and bottom surfaces of the unbonded portions. The ratio of the thickness of at least any 80% of the unbonded portions to at least any 80% of the bonded portions can be at least 2:1, or at least 3:1, or at least 4:1, or at least 5:1, or at least 6:1.

The process for thermally bonding the web is an ultrasonic process. This process generates heat energy through localized frictional forces created by ultrasonics. The ultrasonic vibrations cause alternating compressive forces, and the resulting stresses on the fibers are converted to heat energy which can soften the localized area of fibers presses against each other. Once the ultrasonic vibration is discontinued, the local area cools and solidifies the bond points. The ultrasonic welding process is particularly well suited for spot or pattern bonding the nonwoven web to make a bonded fabric, or to spot or pattern bond fabrics made from the nonwoven web. The ultrasonic welding technique can be used to bond fabrics to itself or to other fabrics and webs to make patterned composites and laminates.

The articles that can be produced through thermally bonding nonwoven webs can include wipes, filters, non-medical garments such as shirts or pants or jackets or socks or undergarments, geotextiles, roofing felts, insoles, paper maker felts, fiberfill webs, needle felts including floor coverings, furniture fill and fabric, sanitary products, medical products such as wound dressings or bandages or sterilization wraps or medical bedding, medical garments such as surgical caps and hoods or face masks or drapes or surgical gowns or caps, automobile interior fabric and cushion fill, bedding (comforters, mattresses), protective clothes, moisture permeable heat retention films and sheets for agriculture/crop protection, carpet backing webs, packing material, wall paper fabrics, art paper-fabric, clothing including interlinings, construction insulation webs, coverstock, upholstery, food coverings, tea bags, personal care products such as diapers or adult incontinence products or feminine hygiene products or training pants, protective covers for vehicles or outdoor equipment, outdoor table covers, and other outdoor fabric covers such as tarpaulins or canopies or tents or agricultural fabrics.

The fabric or wipes may be cut into suitable shapes such as rectangles. The wiped may be treated (e.g. coated, impregnated, moistened) with additives such as surfactants, biocides, cleaners, disinfectants, cosmetics, medicaments, or any other additive to provide end use functionality.

In embodiments, the ultrasonic bonding processes (as described herein) can achieve a bond strength of an average load (over a 4 inch delamination length) of at least 1.0, or at least 1.5, or at least 2.0, or at least 2.5, or at least 3.0, or at least 3.5, or at least 4.0 N/50 cm, as measured by peel strength in accordance with ASTM D2724 (for material as received using the procedure under section 11 for bonded and fused fabrics).

In embodiments, the ultrasonic bonding processes (as described herein) can achieve a bond strength of peak load of at least 2.0, or at least 2.5, or at least 3.0, or at least 3.5, or at least 4.0, or at least 4.5, or at least 5.0, or at least 5.5, or at least 6.0, or at least 6.5, or at least 7.0 N, as measured by peel strength in accordance with ASTM D2724 (for material as received using the procedure under section 11 for bonded and fused fabrics).

In one embodiment or in combination with any of the mentioned embodiments, there is now provided a process for bonding a fabric containing cellulose ester fibers, where the fabric has a tensile break force of at least 1400 grams, or least 1500 grams, or least 1600 grams, or least 1700 grams, or least 1800 grams, or least 1900 grams, or least 2000 grams, or least 2100 grams, or least 2200 grams, or least 2300 grams, or least 2400 grams, or least 2500 grams, or least 2600 grams, or least 2700 grams, or at least 2800 grams, or at least 2900 grams, or at least 3000 grams.

In one embodiment or in combination with any of the mentioned embodiments, there is now provided a process for bonding a fabric containing cellulose ester fibers, where the fabric has a toughness of at least 6000 grams, or least 7000 grams, or least 8000 grams, or least 9000 grams, or least 10000 grams, or least 11000 grams, or least 12000 grams, or least 13000 grams, or least 14000 grams, or least 15000 grams, or least 16000 grams, or least 17000 grams.

There is also now provided a process for bonding a fabric that has a high tensile strength relative to the basis weight of the nonwoven web. In one embodiment or in combination with any of the mentioned embodiments, the fabric containing cellulose ester fibers can have a machine direction tensile break force in grams per basis weight in gsm of the nonwoven web of at least 20 g/gsm, or at least 25 g/gsm, or at least 30 g/gsm, or at least 35 g/gsm, or at least 40 g/gsm, or at least 45 g/gsm, or at least 50 g/gsm, or at least 55 g/gsm, or at least 60 g/gsm.

There is also now provided a process for bonding a fabric that has a high toughness relative to the basis weight of the nonwoven web. In one embodiment or in combination with any of the mentioned embodiments, the fabric containing cellulose ester fibers can have a machine direction toughness in grams per basis weight in gsm of the nonwoven web of at least 100 g/gsm, or at least 125 g/gsm, or at least 150 g/gsm, or at least 175 g/gsm, or at least 200 g/gsm, or at least 225 g/gsm, or at least 250 g/gsm, or at least 275 g/gsm, or at least 300 g/gsm.

EXAMPLES Example 1

Rolls of nonwoven fabrics were made by carding a mixture of base fibers and binder fibers into a nonwoven web and then hydroentangling the fibers in the web to produce a nonwoven. The binder fiber used in the examples was Vestera™ 1.8R1738-A cellulose acetate fibers (CA Fiber) available from Eastman Chemical of Kingsport Tenn., having a cut length of 38 mm and a dpf of 1.8. The base fiber used in the examples were high crystalline rayon and low crystalline rayon. The high crystalline rayon was Tencel™ rayon fibers (HC Rayon) available from Lenzing Aktiengesellschaft of Lenzing, Austria. The low crystalline rayon was Viscose rayon fibers (LC Rayon) available from Lenzing Aktiengesellschaft of Lenzing, Austria.

Rolls of 3 different nonwoven blends were made as discussed above. A standard diaper grade cover stack polypropylene (PP) nonwoven having a basis weight of 17 gsm made from 2.2 dpf PP filaments (PPNW) was also used in the testing. The nonwoven composition and basis weight for each sample tested is listed below in table 2.

TABLE 2 Test Rolls Composition (wt %) Basis Wt. Roll CA Fiber HC Rayon LC Rayon PP (gsm) Roll 1 50 0 50 0 50 Roll 2 0 50 50 0 50 Roll 3 50 50 0 0 50 Roll 4 0 0 0 100 17

Example 2

Different combinations of the nonwoven rolls were laminated together using ultrasonic bonding and evaluated to determine the effect of the material composition on peel strength.

Each lamination was tested to evaluate peel strength in accordance with ASTM D2724 for material as received using the procedure under section 11 for bonded and fused fabrics. The different combinations tested and the results for average load (over 4 inch delamination length) and peak load are listed in table 3.

TABLE 3 Ultrasonic Bond Strength Lamination Avg. Load Peak Load Sample Rolls (N/50 cm) (N) 1 1 and 1 4.3 7.3 2 2 and 2 0.02 0.1 3 3 and 3 1.2 2.4 4 1 and 2 0.2 0.3 5 2 and 4 2.6 5.3 6 1 and 4 4.3 7.3

The rolls listed in table 3 were laminated on a roll to roll ultrasonic laminator that had a 20 kHz system with a CSI MS 200/45/16 Sonotrode and an Ultrabond digital 48.20 Generator. For all samples a star shaped anvil was used having an engraving depth of 0.75 mm and a width of 300 mm. Samples 1 and 2 used an unwind tension of 5 Nm and the other samples used an unwind tension of 10 Nm. All samples used a rewind tension of 12 Nm. The welding and generator parameters for each sample are listed below in table 4.

TABLE 4 Operating Parameters Welding Parameters Generator Parameters Lamination Force Amplitude Frequency Power Sample (N) Step Pos. (%) (kHz) (W) 1 950 7721 100 20100 800 2 1150 7715 100 20050 850 3 1050 7640 100 20060 800 4 1050 7706 100 20085 850 5 800 7725 100 20111 500 6 600 7640 100 20060 600

A review of table 3 reveals that the lamination samples of nonwovens that both contained binder fibers had significant improvement compared to laminations where only one (or neither) nonwoven had binder fibers. Lamination samples of a nonwoven containing the CA fiber and LC Rayon fiber had the highest bond strength. Lamination samples where only one nonwoven had binder fibers showed some improvement in bond strength over lamination samples of nonwovens without any binder fibers. 

What we claim is:
 1. A process for bonding nonwoven webs comprising: a) providing a nonwoven web comprised of base fibers in an amount from 0 to 85 wt % and binder fibers in an amount from 15 to 100 wt %, based on the total weight of the nonwoven web; and b) ultrasonically bonding the nonwoven web to itself, wherein the binder fibers comprise cellulose ester fibers.
 2. The process according to claim 1, wherein the binder fibers comprise 80 wt % or more of cellulose acetate fibers.
 3. The process according to claim 1, wherein the binder fibers are 100 wt % cellulose acetate fibers.
 4. The process according to claim 1, wherein the base fibers comprise non-thermoplastic cellulose fibers.
 5. The process according to claim 1, wherein the base fibers comprise 80 wt % or more of non-thermoplastic cellulose fibers.
 6. The process according to claim 1, wherein the ultrasonic bonding forms a seam having a breaking strength that is at least 40% of the breaking strength of a single-stitch seam.
 7. A process for bonding nonwoven webs comprising: a) providing a first nonwoven web comprised of first base fibers in an amount from 0 to 85 wt % and first binder fibers in an amount from 15 to 100 wt %, based on the total weight of the first nonwoven web; and b) ultrasonically bonding the first nonwoven web to itself or to a second nonwoven web comprised of second base fibers and second binder fibers, wherein the first binder fibers comprise cellulose ester fibers.
 8. The process according to claim 7, wherein the first binder fibers comprise 80 wt % or more of cellulose acetate fibers.
 9. The process according to claim 7, wherein the first base fibers comprise non-thermoplastic cellulose fibers.
 10. A process for bonding nonwoven webs comprising: a) providing a first nonwoven web comprised of first base fibers in an amount from 0 to 85 wt % and first binder fibers in an amount from 15 to 100 wt %, based on the total weight of the first nonwoven web; and b) ultrasonically bonding the first nonwoven web to a second nonwoven web comprised of second base fibers and second binder fibers, wherein the first binder fibers comprise cellulose ester fibers.
 11. The process according to claim 10, wherein the first binder fibers comprise 80 wt % or more of cellulose acetate fibers.
 12. The process according to claim 10, wherein the first base fibers comprise non-thermoplastic cellulose fibers.
 13. The process according to claim 10, wherein the second nonwoven web comprises second base fibers in an amount from 0 to 85 wt % and second binder fibers in an amount from 15 to 100 wt %, based on the total weight of the second nonwoven web.
 14. The process according to claim 10, wherein the second binder fibers comprise cellulose ester fibers.
 15. The process according to claim 21, wherein the second binder fibers comprise 80 wt % or more of cellulose acetate fibers.
 16. The process according to claim 10, wherein the second base fibers comprise 80 wt % or more of non-thermoplastic cellulose fibers.
 17. The process according to claim 10, wherein the process further comprises forming a laminate of said first and second nonwoven webs.
 18. The process according to claim 17, wherein the laminate is not formed using an adhesive and does not comprise an adhesive.
 19. The process according to claim 18, wherein the laminate is formed by bonding said first and second nonwoven webs using only ultrasonic bonding.
 20. The process according to claim 17, wherein the laminate is biodegradable and compostable. 